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Posted to commits@flink.apache.org by dw...@apache.org on 2018/12/17 08:25:20 UTC

[flink] 05/06: [FLINK-7599][table] Throw exception on DISTINCT in aggregations in MATCH_RECOGNIZE

This is an automated email from the ASF dual-hosted git repository.

dwysakowicz pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/flink.git

commit 41b3a3bb6fdbd2c22a3cc76317ada2f7c5bb98f3
Author: Dawid Wysakowicz <dw...@apache.org>
AuthorDate: Thu Nov 29 10:41:49 2018 +0100

    [FLINK-7599][table] Throw exception on DISTINCT in aggregations in MATCH_RECOGNIZE
---
 docs/dev/table/streaming/match_recognize.md        |    2 +-
 .../calcite/sql/validate/SqlValidatorImpl.java     | 6340 ++++++++++++++++++++
 .../table/match/MatchRecognizeValidationTest.scala |   21 +
 .../runtime/stream/sql/MatchRecognizeITCase.scala  |    2 +-
 4 files changed, 6363 insertions(+), 2 deletions(-)

diff --git a/docs/dev/table/streaming/match_recognize.md b/docs/dev/table/streaming/match_recognize.md
index 7c9ade4..fc16596 100644
--- a/docs/dev/table/streaming/match_recognize.md
+++ b/docs/dev/table/streaming/match_recognize.md
@@ -959,4 +959,4 @@ Unsupported features include:
 * Extracting time attributes - there is currently no possibility to get a time attribute for subsequent time-based operations.
 * `MATCH_RECOGNIZE` is supported only for SQL. There is no equivalent in the Table API.
 * Aggregations:
-  * distinct aggregations are not supported. Moreover if specified it will be silently dropped unfortunately.
+  * distinct aggregations are not supported.
diff --git a/flink-libraries/flink-table/src/main/java/org/apache/calcite/sql/validate/SqlValidatorImpl.java b/flink-libraries/flink-table/src/main/java/org/apache/calcite/sql/validate/SqlValidatorImpl.java
new file mode 100644
index 0000000..f318166
--- /dev/null
+++ b/flink-libraries/flink-table/src/main/java/org/apache/calcite/sql/validate/SqlValidatorImpl.java
@@ -0,0 +1,6340 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to you under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.calcite.sql.validate;
+
+import org.apache.calcite.config.NullCollation;
+import org.apache.calcite.jdbc.CalciteSchema;
+import org.apache.calcite.linq4j.Ord;
+import org.apache.calcite.linq4j.function.Function2;
+import org.apache.calcite.linq4j.function.Functions;
+import org.apache.calcite.plan.RelOptTable;
+import org.apache.calcite.plan.RelOptUtil;
+import org.apache.calcite.prepare.Prepare;
+import org.apache.calcite.rel.type.DynamicRecordType;
+import org.apache.calcite.rel.type.RelDataType;
+import org.apache.calcite.rel.type.RelDataTypeFactory;
+import org.apache.calcite.rel.type.RelDataTypeField;
+import org.apache.calcite.rel.type.RelDataTypeSystem;
+import org.apache.calcite.rel.type.RelRecordType;
+import org.apache.calcite.rex.RexBuilder;
+import org.apache.calcite.rex.RexNode;
+import org.apache.calcite.rex.RexPatternFieldRef;
+import org.apache.calcite.rex.RexVisitor;
+import org.apache.calcite.runtime.CalciteContextException;
+import org.apache.calcite.runtime.CalciteException;
+import org.apache.calcite.runtime.Feature;
+import org.apache.calcite.runtime.Resources;
+import org.apache.calcite.schema.ColumnStrategy;
+import org.apache.calcite.schema.Table;
+import org.apache.calcite.schema.impl.ModifiableViewTable;
+import org.apache.calcite.sql.JoinConditionType;
+import org.apache.calcite.sql.JoinType;
+import org.apache.calcite.sql.SqlAccessEnum;
+import org.apache.calcite.sql.SqlAccessType;
+import org.apache.calcite.sql.SqlBasicCall;
+import org.apache.calcite.sql.SqlCall;
+import org.apache.calcite.sql.SqlCallBinding;
+import org.apache.calcite.sql.SqlDataTypeSpec;
+import org.apache.calcite.sql.SqlDelete;
+import org.apache.calcite.sql.SqlDynamicParam;
+import org.apache.calcite.sql.SqlExplain;
+import org.apache.calcite.sql.SqlFunction;
+import org.apache.calcite.sql.SqlFunctionCategory;
+import org.apache.calcite.sql.SqlIdentifier;
+import org.apache.calcite.sql.SqlInsert;
+import org.apache.calcite.sql.SqlIntervalLiteral;
+import org.apache.calcite.sql.SqlIntervalQualifier;
+import org.apache.calcite.sql.SqlJoin;
+import org.apache.calcite.sql.SqlKind;
+import org.apache.calcite.sql.SqlLiteral;
+import org.apache.calcite.sql.SqlMatchRecognize;
+import org.apache.calcite.sql.SqlMerge;
+import org.apache.calcite.sql.SqlNode;
+import org.apache.calcite.sql.SqlNodeList;
+import org.apache.calcite.sql.SqlOperator;
+import org.apache.calcite.sql.SqlOperatorTable;
+import org.apache.calcite.sql.SqlOrderBy;
+import org.apache.calcite.sql.SqlSampleSpec;
+import org.apache.calcite.sql.SqlSelect;
+import org.apache.calcite.sql.SqlSelectKeyword;
+import org.apache.calcite.sql.SqlSyntax;
+import org.apache.calcite.sql.SqlUnresolvedFunction;
+import org.apache.calcite.sql.SqlUpdate;
+import org.apache.calcite.sql.SqlUtil;
+import org.apache.calcite.sql.SqlWindow;
+import org.apache.calcite.sql.SqlWith;
+import org.apache.calcite.sql.SqlWithItem;
+import org.apache.calcite.sql.fun.SqlCase;
+import org.apache.calcite.sql.fun.SqlStdOperatorTable;
+import org.apache.calcite.sql.parser.SqlParserPos;
+import org.apache.calcite.sql.type.AssignableOperandTypeChecker;
+import org.apache.calcite.sql.type.ReturnTypes;
+import org.apache.calcite.sql.type.SqlOperandTypeInference;
+import org.apache.calcite.sql.type.SqlTypeName;
+import org.apache.calcite.sql.type.SqlTypeUtil;
+import org.apache.calcite.sql.util.SqlBasicVisitor;
+import org.apache.calcite.sql.util.SqlShuttle;
+import org.apache.calcite.sql.util.SqlVisitor;
+import org.apache.calcite.sql2rel.InitializerContext;
+import org.apache.calcite.util.BitString;
+import org.apache.calcite.util.Bug;
+import org.apache.calcite.util.ImmutableBitSet;
+import org.apache.calcite.util.ImmutableIntList;
+import org.apache.calcite.util.ImmutableNullableList;
+import org.apache.calcite.util.Litmus;
+import org.apache.calcite.util.Pair;
+import org.apache.calcite.util.Static;
+import org.apache.calcite.util.Util;
+import org.apache.calcite.util.trace.CalciteTrace;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Lists;
+import com.google.common.collect.Sets;
+
+import org.slf4j.Logger;
+
+import java.math.BigDecimal;
+import java.math.BigInteger;
+import java.util.AbstractList;
+import java.util.ArrayDeque;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Calendar;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Deque;
+import java.util.GregorianCalendar;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.IdentityHashMap;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+import java.util.function.Supplier;
+
+import static org.apache.calcite.sql.SqlUtil.stripAs;
+import static org.apache.calcite.util.Static.RESOURCE;
+
+/*
+ * THIS FILE HAS BEEN COPIED FROM THE APACHE CALCITE PROJECT UNTIL CALCITE-2707 IS FIXED.
+ * (Added lines: 5937-5943)
+ */
+
+/**
+ * Default implementation of {@link SqlValidator}.
+ */
+public class SqlValidatorImpl implements SqlValidatorWithHints {
+	//~ Static fields/initializers ---------------------------------------------
+
+	public static final Logger TRACER = CalciteTrace.PARSER_LOGGER;
+
+	/**
+	 * Alias generated for the source table when rewriting UPDATE to MERGE.
+	 */
+	public static final String UPDATE_SRC_ALIAS = "SYS$SRC";
+
+	/**
+	 * Alias generated for the target table when rewriting UPDATE to MERGE if no
+	 * alias was specified by the user.
+	 */
+	public static final String UPDATE_TGT_ALIAS = "SYS$TGT";
+
+	/**
+	 * Alias prefix generated for source columns when rewriting UPDATE to MERGE.
+	 */
+	public static final String UPDATE_ANON_PREFIX = "SYS$ANON";
+
+	//~ Instance fields --------------------------------------------------------
+
+	private final SqlOperatorTable opTab;
+	final SqlValidatorCatalogReader catalogReader;
+
+	/**
+	 * Maps ParsePosition strings to the {@link SqlIdentifier} identifier
+	 * objects at these positions
+	 */
+	protected final Map<String, IdInfo> idPositions = new HashMap<>();
+
+	/**
+	 * Maps {@link SqlNode query node} objects to the {@link SqlValidatorScope}
+	 * scope created from them.
+	 */
+	protected final Map<SqlNode, SqlValidatorScope> scopes =
+		new IdentityHashMap<>();
+
+	/**
+	 * Maps a {@link SqlSelect} node to the scope used by its WHERE and HAVING
+	 * clauses.
+	 */
+	private final Map<SqlSelect, SqlValidatorScope> whereScopes =
+		new IdentityHashMap<>();
+
+	/**
+	 * Maps a {@link SqlSelect} node to the scope used by its GROUP BY clause.
+	 */
+	private final Map<SqlSelect, SqlValidatorScope> groupByScopes =
+		new IdentityHashMap<>();
+
+	/**
+	 * Maps a {@link SqlSelect} node to the scope used by its SELECT and HAVING
+	 * clauses.
+	 */
+	private final Map<SqlSelect, SqlValidatorScope> selectScopes =
+		new IdentityHashMap<>();
+
+	/**
+	 * Maps a {@link SqlSelect} node to the scope used by its ORDER BY clause.
+	 */
+	private final Map<SqlSelect, SqlValidatorScope> orderScopes =
+		new IdentityHashMap<>();
+
+	/**
+	 * Maps a {@link SqlSelect} node that is the argument to a CURSOR
+	 * constructor to the scope of the result of that select node
+	 */
+	private final Map<SqlSelect, SqlValidatorScope> cursorScopes =
+		new IdentityHashMap<>();
+
+	/**
+	 * The name-resolution scope of a LATERAL TABLE clause.
+	 */
+	private TableScope tableScope = null;
+
+	/**
+	 * Maps a {@link SqlNode node} to the
+	 * {@link SqlValidatorNamespace namespace} which describes what columns they
+	 * contain.
+	 */
+	protected final Map<SqlNode, SqlValidatorNamespace> namespaces =
+		new IdentityHashMap<>();
+
+	/**
+	 * Set of select expressions used as cursor definitions. In standard SQL,
+	 * only the top-level SELECT is a cursor; Calcite extends this with
+	 * cursors as inputs to table functions.
+	 */
+	private final Set<SqlNode> cursorSet = Sets.newIdentityHashSet();
+
+	/**
+	 * Stack of objects that maintain information about function calls. A stack
+	 * is needed to handle nested function calls. The function call currently
+	 * being validated is at the top of the stack.
+	 */
+	protected final Deque<FunctionParamInfo> functionCallStack =
+		new ArrayDeque<>();
+
+	private int nextGeneratedId;
+	protected final RelDataTypeFactory typeFactory;
+
+	/** The type of dynamic parameters until a type is imposed on them. */
+	protected final RelDataType unknownType;
+	private final RelDataType booleanType;
+
+	/**
+	 * Map of derived RelDataType for each node. This is an IdentityHashMap
+	 * since in some cases (such as null literals) we need to discriminate by
+	 * instance.
+	 */
+	private final Map<SqlNode, RelDataType> nodeToTypeMap =
+		new IdentityHashMap<>();
+	private final AggFinder aggFinder;
+	private final AggFinder aggOrOverFinder;
+	private final AggFinder aggOrOverOrGroupFinder;
+	private final AggFinder groupFinder;
+	private final AggFinder overFinder;
+	private final SqlConformance conformance;
+	private final Map<SqlNode, SqlNode> originalExprs = new HashMap<>();
+
+	private SqlNode top;
+
+	// REVIEW jvs 30-June-2006: subclasses may override shouldExpandIdentifiers
+	// in a way that ignores this; we should probably get rid of the protected
+	// method and always use this variable (or better, move preferences like
+	// this to a separate "parameter" class)
+	protected boolean expandIdentifiers;
+
+	protected boolean expandColumnReferences;
+
+	private boolean rewriteCalls;
+
+	private NullCollation nullCollation = NullCollation.HIGH;
+
+	// TODO jvs 11-Dec-2008:  make this local to performUnconditionalRewrites
+	// if it's OK to expand the signature of that method.
+	private boolean validatingSqlMerge;
+
+	private boolean inWindow;                        // Allow nested aggregates
+
+	private final SqlValidatorImpl.ValidationErrorFunction validationErrorFunction =
+		new SqlValidatorImpl.ValidationErrorFunction();
+
+	//~ Constructors -----------------------------------------------------------
+
+	/**
+	 * Creates a validator.
+	 *
+	 * @param opTab         Operator table
+	 * @param catalogReader Catalog reader
+	 * @param typeFactory   Type factory
+	 * @param conformance   Compatibility mode
+	 */
+	protected SqlValidatorImpl(
+		SqlOperatorTable opTab,
+		SqlValidatorCatalogReader catalogReader,
+		RelDataTypeFactory typeFactory,
+		SqlConformance conformance) {
+		this.opTab = Objects.requireNonNull(opTab);
+		this.catalogReader = Objects.requireNonNull(catalogReader);
+		this.typeFactory = Objects.requireNonNull(typeFactory);
+		this.conformance = Objects.requireNonNull(conformance);
+
+		unknownType = typeFactory.createUnknownType();
+		booleanType = typeFactory.createSqlType(SqlTypeName.BOOLEAN);
+
+		rewriteCalls = true;
+		expandColumnReferences = true;
+		aggFinder = new AggFinder(opTab, false, true, false, null);
+		aggOrOverFinder = new AggFinder(opTab, true, true, false, null);
+		overFinder = new AggFinder(opTab, true, false, false, aggOrOverFinder);
+		groupFinder = new AggFinder(opTab, false, false, true, null);
+		aggOrOverOrGroupFinder = new AggFinder(opTab, true, true, true, null);
+	}
+
+	//~ Methods ----------------------------------------------------------------
+
+	public SqlConformance getConformance() {
+		return conformance;
+	}
+
+	public SqlValidatorCatalogReader getCatalogReader() {
+		return catalogReader;
+	}
+
+	public SqlOperatorTable getOperatorTable() {
+		return opTab;
+	}
+
+	public RelDataTypeFactory getTypeFactory() {
+		return typeFactory;
+	}
+
+	public RelDataType getUnknownType() {
+		return unknownType;
+	}
+
+	public SqlNodeList expandStar(
+		SqlNodeList selectList,
+		SqlSelect select,
+		boolean includeSystemVars) {
+		final List<SqlNode> list = new ArrayList<>();
+		final List<Map.Entry<String, RelDataType>> types = new ArrayList<>();
+		for (int i = 0; i < selectList.size(); i++) {
+			final SqlNode selectItem = selectList.get(i);
+			final RelDataType originalType = getValidatedNodeTypeIfKnown(selectItem);
+			expandSelectItem(
+				selectItem,
+				select,
+				Util.first(originalType, unknownType),
+				list,
+				catalogReader.nameMatcher().createSet(),
+				types,
+				includeSystemVars);
+		}
+		getRawSelectScope(select).setExpandedSelectList(list);
+		return new SqlNodeList(list, SqlParserPos.ZERO);
+	}
+
+	// implement SqlValidator
+	public void declareCursor(SqlSelect select, SqlValidatorScope parentScope) {
+		cursorSet.add(select);
+
+		// add the cursor to a map that maps the cursor to its select based on
+		// the position of the cursor relative to other cursors in that call
+		FunctionParamInfo funcParamInfo = functionCallStack.peek();
+		Map<Integer, SqlSelect> cursorMap = funcParamInfo.cursorPosToSelectMap;
+		int numCursors = cursorMap.size();
+		cursorMap.put(numCursors, select);
+
+		// create a namespace associated with the result of the select
+		// that is the argument to the cursor constructor; register it
+		// with a scope corresponding to the cursor
+		SelectScope cursorScope = new SelectScope(parentScope, null, select);
+		cursorScopes.put(select, cursorScope);
+		final SelectNamespace selectNs = createSelectNamespace(select, select);
+		String alias = deriveAlias(select, nextGeneratedId++);
+		registerNamespace(cursorScope, alias, selectNs, false);
+	}
+
+	// implement SqlValidator
+	public void pushFunctionCall() {
+		FunctionParamInfo funcInfo = new FunctionParamInfo();
+		functionCallStack.push(funcInfo);
+	}
+
+	// implement SqlValidator
+	public void popFunctionCall() {
+		functionCallStack.pop();
+	}
+
+	// implement SqlValidator
+	public String getParentCursor(String columnListParamName) {
+		FunctionParamInfo funcParamInfo = functionCallStack.peek();
+		Map<String, String> parentCursorMap =
+			funcParamInfo.columnListParamToParentCursorMap;
+		return parentCursorMap.get(columnListParamName);
+	}
+
+	/**
+	 * If <code>selectItem</code> is "*" or "TABLE.*", expands it and returns
+	 * true; otherwise writes the unexpanded item.
+	 *
+	 * @param selectItem        Select-list item
+	 * @param select            Containing select clause
+	 * @param selectItems       List that expanded items are written to
+	 * @param aliases           Set of aliases
+	 * @param fields            List of field names and types, in alias order
+	 * @param includeSystemVars If true include system vars in lists
+	 * @return Whether the node was expanded
+	 */
+	private boolean expandSelectItem(
+		final SqlNode selectItem,
+		SqlSelect select,
+		RelDataType targetType,
+		List<SqlNode> selectItems,
+		Set<String> aliases,
+		List<Map.Entry<String, RelDataType>> fields,
+		final boolean includeSystemVars) {
+		final SelectScope scope = (SelectScope) getWhereScope(select);
+		if (expandStar(selectItems, aliases, fields, includeSystemVars, scope,
+			selectItem)) {
+			return true;
+		}
+
+		// Expand the select item: fully-qualify columns, and convert
+		// parentheses-free functions such as LOCALTIME into explicit function
+		// calls.
+		SqlNode expanded = expand(selectItem, scope);
+		final String alias =
+			deriveAlias(
+				selectItem,
+				aliases.size());
+
+		// If expansion has altered the natural alias, supply an explicit 'AS'.
+		final SqlValidatorScope selectScope = getSelectScope(select);
+		if (expanded != selectItem) {
+			String newAlias =
+				deriveAlias(
+					expanded,
+					aliases.size());
+			if (!newAlias.equals(alias)) {
+				expanded =
+					SqlStdOperatorTable.AS.createCall(
+						selectItem.getParserPosition(),
+						expanded,
+						new SqlIdentifier(alias, SqlParserPos.ZERO));
+				deriveTypeImpl(selectScope, expanded);
+			}
+		}
+
+		selectItems.add(expanded);
+		aliases.add(alias);
+
+		inferUnknownTypes(targetType, scope, expanded);
+		final RelDataType type = deriveType(selectScope, expanded);
+		setValidatedNodeType(expanded, type);
+		fields.add(Pair.of(alias, type));
+		return false;
+	}
+
+	private boolean expandStar(List<SqlNode> selectItems, Set<String> aliases,
+		List<Map.Entry<String, RelDataType>> fields, boolean includeSystemVars,
+		SelectScope scope, SqlNode node) {
+		if (!(node instanceof SqlIdentifier)) {
+			return false;
+		}
+		final SqlIdentifier identifier = (SqlIdentifier) node;
+		if (!identifier.isStar()) {
+			return false;
+		}
+		final SqlParserPos startPosition = identifier.getParserPosition();
+		switch (identifier.names.size()) {
+			case 1:
+				boolean hasDynamicStruct = false;
+				for (ScopeChild child : scope.children) {
+					final int before = fields.size();
+					if (child.namespace.getRowType().isDynamicStruct()) {
+						hasDynamicStruct = true;
+						// don't expand star if the underneath table is dynamic.
+						// Treat this star as a special field in validation/conversion and
+						// wait until execution time to expand this star.
+						final SqlNode exp =
+							new SqlIdentifier(
+								ImmutableList.of(child.name,
+									DynamicRecordType.DYNAMIC_STAR_PREFIX),
+								startPosition);
+						addToSelectList(
+							selectItems,
+							aliases,
+							fields,
+							exp,
+							scope,
+							includeSystemVars);
+					} else {
+						final SqlNode from = child.namespace.getNode();
+						final SqlValidatorNamespace fromNs = getNamespace(from, scope);
+						assert fromNs != null;
+						final RelDataType rowType = fromNs.getRowType();
+						for (RelDataTypeField field : rowType.getFieldList()) {
+							String columnName = field.getName();
+
+							// TODO: do real implicit collation here
+							final SqlIdentifier exp =
+								new SqlIdentifier(
+									ImmutableList.of(child.name, columnName),
+									startPosition);
+							// Don't add expanded rolled up columns
+							if (!isRolledUpColumn(exp, scope)) {
+								addOrExpandField(
+									selectItems,
+									aliases,
+									fields,
+									includeSystemVars,
+									scope,
+									exp,
+									field);
+							}
+						}
+					}
+					if (child.nullable) {
+						for (int i = before; i < fields.size(); i++) {
+							final Map.Entry<String, RelDataType> entry = fields.get(i);
+							final RelDataType type = entry.getValue();
+							if (!type.isNullable()) {
+								fields.set(i,
+									Pair.of(entry.getKey(),
+										typeFactory.createTypeWithNullability(type, true)));
+							}
+						}
+					}
+				}
+				// If NATURAL JOIN or USING is present, move key fields to the front of
+				// the list, per standard SQL. Disabled if there are dynamic fields.
+				if (!hasDynamicStruct || Bug.CALCITE_2400_FIXED) {
+					new Permute(scope.getNode().getFrom(), 0).permute(selectItems, fields);
+				}
+				return true;
+
+			default:
+				final SqlIdentifier prefixId = identifier.skipLast(1);
+				final SqlValidatorScope.ResolvedImpl resolved =
+					new SqlValidatorScope.ResolvedImpl();
+				final SqlNameMatcher nameMatcher =
+					scope.validator.catalogReader.nameMatcher();
+				scope.resolve(prefixId.names, nameMatcher, true, resolved);
+				if (resolved.count() == 0) {
+					// e.g. "select s.t.* from e"
+					// or "select r.* from e"
+					throw newValidationError(prefixId,
+						RESOURCE.unknownIdentifier(prefixId.toString()));
+				}
+				final RelDataType rowType = resolved.only().rowType();
+				if (rowType.isDynamicStruct()) {
+					// don't expand star if the underneath table is dynamic.
+					addToSelectList(
+						selectItems,
+						aliases,
+						fields,
+						prefixId.plus(DynamicRecordType.DYNAMIC_STAR_PREFIX, startPosition),
+						scope,
+						includeSystemVars);
+				} else if (rowType.isStruct()) {
+					for (RelDataTypeField field : rowType.getFieldList()) {
+						String columnName = field.getName();
+
+						// TODO: do real implicit collation here
+						addOrExpandField(
+							selectItems,
+							aliases,
+							fields,
+							includeSystemVars,
+							scope,
+							prefixId.plus(columnName, startPosition),
+							field);
+					}
+				} else {
+					throw newValidationError(prefixId, RESOURCE.starRequiresRecordType());
+				}
+				return true;
+		}
+	}
+
+	private SqlNode maybeCast(SqlNode node, RelDataType currentType,
+		RelDataType desiredType) {
+		return currentType.equals(desiredType)
+			|| (currentType.isNullable() != desiredType.isNullable()
+				    && typeFactory.createTypeWithNullability(currentType,
+			desiredType.isNullable()).equals(desiredType))
+			? node
+			: SqlStdOperatorTable.CAST.createCall(SqlParserPos.ZERO,
+			node, SqlTypeUtil.convertTypeToSpec(desiredType));
+	}
+
+	private boolean addOrExpandField(List<SqlNode> selectItems, Set<String> aliases,
+		List<Map.Entry<String, RelDataType>> fields, boolean includeSystemVars,
+		SelectScope scope, SqlIdentifier id, RelDataTypeField field) {
+		switch (field.getType().getStructKind()) {
+			case PEEK_FIELDS:
+			case PEEK_FIELDS_DEFAULT:
+				final SqlNode starExp = id.plusStar();
+				expandStar(
+					selectItems,
+					aliases,
+					fields,
+					includeSystemVars,
+					scope,
+					starExp);
+				return true;
+
+			default:
+				addToSelectList(
+					selectItems,
+					aliases,
+					fields,
+					id,
+					scope,
+					includeSystemVars);
+		}
+
+		return false;
+	}
+
+	public SqlNode validate(SqlNode topNode) {
+		SqlValidatorScope scope = new EmptyScope(this);
+		scope = new CatalogScope(scope, ImmutableList.of("CATALOG"));
+		final SqlNode topNode2 = validateScopedExpression(topNode, scope);
+		final RelDataType type = getValidatedNodeType(topNode2);
+		Util.discard(type);
+		return topNode2;
+	}
+
+	public List<SqlMoniker> lookupHints(SqlNode topNode, SqlParserPos pos) {
+		SqlValidatorScope scope = new EmptyScope(this);
+		SqlNode outermostNode = performUnconditionalRewrites(topNode, false);
+		cursorSet.add(outermostNode);
+		if (outermostNode.isA(SqlKind.TOP_LEVEL)) {
+			registerQuery(
+				scope,
+				null,
+				outermostNode,
+				outermostNode,
+				null,
+				false);
+		}
+		final SqlValidatorNamespace ns = getNamespace(outermostNode);
+		if (ns == null) {
+			throw new AssertionError("Not a query: " + outermostNode);
+		}
+		Collection<SqlMoniker> hintList = Sets.newTreeSet(SqlMoniker.COMPARATOR);
+		lookupSelectHints(ns, pos, hintList);
+		return ImmutableList.copyOf(hintList);
+	}
+
+	public SqlMoniker lookupQualifiedName(SqlNode topNode, SqlParserPos pos) {
+		final String posString = pos.toString();
+		IdInfo info = idPositions.get(posString);
+		if (info != null) {
+			final SqlQualified qualified = info.scope.fullyQualify(info.id);
+			return new SqlIdentifierMoniker(qualified.identifier);
+		} else {
+			return null;
+		}
+	}
+
+	/**
+	 * Looks up completion hints for a syntactically correct select SQL that has
+	 * been parsed into an expression tree.
+	 *
+	 * @param select   the Select node of the parsed expression tree
+	 * @param pos      indicates the position in the sql statement we want to get
+	 *                 completion hints for
+	 * @param hintList list of {@link SqlMoniker} (sql identifiers) that can
+	 *                 fill in at the indicated position
+	 */
+	void lookupSelectHints(
+		SqlSelect select,
+		SqlParserPos pos,
+		Collection<SqlMoniker> hintList) {
+		IdInfo info = idPositions.get(pos.toString());
+		if ((info == null) || (info.scope == null)) {
+			SqlNode fromNode = select.getFrom();
+			final SqlValidatorScope fromScope = getFromScope(select);
+			lookupFromHints(fromNode, fromScope, pos, hintList);
+		} else {
+			lookupNameCompletionHints(info.scope, info.id.names,
+				info.id.getParserPosition(), hintList);
+		}
+	}
+
+	private void lookupSelectHints(
+		SqlValidatorNamespace ns,
+		SqlParserPos pos,
+		Collection<SqlMoniker> hintList) {
+		final SqlNode node = ns.getNode();
+		if (node instanceof SqlSelect) {
+			lookupSelectHints((SqlSelect) node, pos, hintList);
+		}
+	}
+
+	private void lookupFromHints(
+		SqlNode node,
+		SqlValidatorScope scope,
+		SqlParserPos pos,
+		Collection<SqlMoniker> hintList) {
+		final SqlValidatorNamespace ns = getNamespace(node);
+		if (ns.isWrapperFor(IdentifierNamespace.class)) {
+			IdentifierNamespace idNs = ns.unwrap(IdentifierNamespace.class);
+			final SqlIdentifier id = idNs.getId();
+			for (int i = 0; i < id.names.size(); i++) {
+				if (pos.toString().equals(
+					id.getComponent(i).getParserPosition().toString())) {
+					final List<SqlMoniker> objNames = new ArrayList<>();
+					SqlValidatorUtil.getSchemaObjectMonikers(
+						getCatalogReader(),
+						id.names.subList(0, i + 1),
+						objNames);
+					for (SqlMoniker objName : objNames) {
+						if (objName.getType() != SqlMonikerType.FUNCTION) {
+							hintList.add(objName);
+						}
+					}
+					return;
+				}
+			}
+		}
+		switch (node.getKind()) {
+			case JOIN:
+				lookupJoinHints((SqlJoin) node, scope, pos, hintList);
+				break;
+			default:
+				lookupSelectHints(ns, pos, hintList);
+				break;
+		}
+	}
+
+	private void lookupJoinHints(
+		SqlJoin join,
+		SqlValidatorScope scope,
+		SqlParserPos pos,
+		Collection<SqlMoniker> hintList) {
+		SqlNode left = join.getLeft();
+		SqlNode right = join.getRight();
+		SqlNode condition = join.getCondition();
+		lookupFromHints(left, scope, pos, hintList);
+		if (hintList.size() > 0) {
+			return;
+		}
+		lookupFromHints(right, scope, pos, hintList);
+		if (hintList.size() > 0) {
+			return;
+		}
+		final JoinConditionType conditionType = join.getConditionType();
+		final SqlValidatorScope joinScope = scopes.get(join);
+		switch (conditionType) {
+			case ON:
+				condition.findValidOptions(this, joinScope, pos, hintList);
+				return;
+			default:
+
+				// No suggestions.
+				// Not supporting hints for other types such as 'Using' yet.
+				return;
+		}
+	}
+
+	/**
+	 * Populates a list of all the valid alternatives for an identifier.
+	 *
+	 * @param scope    Validation scope
+	 * @param names    Components of the identifier
+	 * @param pos      position
+	 * @param hintList a list of valid options
+	 */
+	public final void lookupNameCompletionHints(
+		SqlValidatorScope scope,
+		List<String> names,
+		SqlParserPos pos,
+		Collection<SqlMoniker> hintList) {
+		// Remove the last part of name - it is a dummy
+		List<String> subNames = Util.skipLast(names);
+
+		if (subNames.size() > 0) {
+			// If there's a prefix, resolve it to a namespace.
+			SqlValidatorNamespace ns = null;
+			for (String name : subNames) {
+				if (ns == null) {
+					final SqlValidatorScope.ResolvedImpl resolved =
+						new SqlValidatorScope.ResolvedImpl();
+					final SqlNameMatcher nameMatcher = catalogReader.nameMatcher();
+					scope.resolve(ImmutableList.of(name), nameMatcher, false, resolved);
+					if (resolved.count() == 1) {
+						ns = resolved.only().namespace;
+					}
+				} else {
+					ns = ns.lookupChild(name);
+				}
+				if (ns == null) {
+					break;
+				}
+			}
+			if (ns != null) {
+				RelDataType rowType = ns.getRowType();
+				for (RelDataTypeField field : rowType.getFieldList()) {
+					hintList.add(
+						new SqlMonikerImpl(
+							field.getName(),
+							SqlMonikerType.COLUMN));
+				}
+			}
+
+			// builtin function names are valid completion hints when the
+			// identifier has only 1 name part
+			findAllValidFunctionNames(names, this, hintList, pos);
+		} else {
+			// No prefix; use the children of the current scope (that is,
+			// the aliases in the FROM clause)
+			scope.findAliases(hintList);
+
+			// If there's only one alias, add all child columns
+			SelectScope selectScope =
+				SqlValidatorUtil.getEnclosingSelectScope(scope);
+			if ((selectScope != null)
+				&& (selectScope.getChildren().size() == 1)) {
+				RelDataType rowType =
+					selectScope.getChildren().get(0).getRowType();
+				for (RelDataTypeField field : rowType.getFieldList()) {
+					hintList.add(
+						new SqlMonikerImpl(
+							field.getName(),
+							SqlMonikerType.COLUMN));
+				}
+			}
+		}
+
+		findAllValidUdfNames(names, this, hintList);
+	}
+
+	private static void findAllValidUdfNames(
+		List<String> names,
+		SqlValidator validator,
+		Collection<SqlMoniker> result) {
+		final List<SqlMoniker> objNames = new ArrayList<>();
+		SqlValidatorUtil.getSchemaObjectMonikers(
+			validator.getCatalogReader(),
+			names,
+			objNames);
+		for (SqlMoniker objName : objNames) {
+			if (objName.getType() == SqlMonikerType.FUNCTION) {
+				result.add(objName);
+			}
+		}
+	}
+
+	private static void findAllValidFunctionNames(
+		List<String> names,
+		SqlValidator validator,
+		Collection<SqlMoniker> result,
+		SqlParserPos pos) {
+		// a function name can only be 1 part
+		if (names.size() > 1) {
+			return;
+		}
+		for (SqlOperator op : validator.getOperatorTable().getOperatorList()) {
+			SqlIdentifier curOpId =
+				new SqlIdentifier(
+					op.getName(),
+					pos);
+
+			final SqlCall call =
+				SqlUtil.makeCall(
+					validator.getOperatorTable(),
+					curOpId);
+			if (call != null) {
+				result.add(
+					new SqlMonikerImpl(
+						op.getName(),
+						SqlMonikerType.FUNCTION));
+			} else {
+				if ((op.getSyntax() == SqlSyntax.FUNCTION)
+					|| (op.getSyntax() == SqlSyntax.PREFIX)) {
+					if (op.getOperandTypeChecker() != null) {
+						String sig = op.getAllowedSignatures();
+						sig = sig.replaceAll("'", "");
+						result.add(
+							new SqlMonikerImpl(
+								sig,
+								SqlMonikerType.FUNCTION));
+						continue;
+					}
+					result.add(
+						new SqlMonikerImpl(
+							op.getName(),
+							SqlMonikerType.FUNCTION));
+				}
+			}
+		}
+	}
+
+	public SqlNode validateParameterizedExpression(
+		SqlNode topNode,
+		final Map<String, RelDataType> nameToTypeMap) {
+		SqlValidatorScope scope = new ParameterScope(this, nameToTypeMap);
+		return validateScopedExpression(topNode, scope);
+	}
+
+	private SqlNode validateScopedExpression(
+		SqlNode topNode,
+		SqlValidatorScope scope) {
+		SqlNode outermostNode = performUnconditionalRewrites(topNode, false);
+		cursorSet.add(outermostNode);
+		top = outermostNode;
+		TRACER.trace("After unconditional rewrite: {}", outermostNode);
+		if (outermostNode.isA(SqlKind.TOP_LEVEL)) {
+			registerQuery(scope, null, outermostNode, outermostNode, null, false);
+		}
+		outermostNode.validate(this, scope);
+		if (!outermostNode.isA(SqlKind.TOP_LEVEL)) {
+			// force type derivation so that we can provide it to the
+			// caller later without needing the scope
+			deriveType(scope, outermostNode);
+		}
+		TRACER.trace("After validation: {}", outermostNode);
+		return outermostNode;
+	}
+
+	public void validateQuery(SqlNode node, SqlValidatorScope scope,
+		RelDataType targetRowType) {
+		final SqlValidatorNamespace ns = getNamespace(node, scope);
+		if (node.getKind() == SqlKind.TABLESAMPLE) {
+			List<SqlNode> operands = ((SqlCall) node).getOperandList();
+			SqlSampleSpec sampleSpec = SqlLiteral.sampleValue(operands.get(1));
+			if (sampleSpec instanceof SqlSampleSpec.SqlTableSampleSpec) {
+				validateFeature(RESOURCE.sQLFeature_T613(), node.getParserPosition());
+			} else if (sampleSpec
+				instanceof SqlSampleSpec.SqlSubstitutionSampleSpec) {
+				validateFeature(RESOURCE.sQLFeatureExt_T613_Substitution(),
+					node.getParserPosition());
+			}
+		}
+
+		validateNamespace(ns, targetRowType);
+		switch (node.getKind()) {
+			case EXTEND:
+				// Until we have a dedicated namespace for EXTEND
+				deriveType(scope, node);
+		}
+		if (node == top) {
+			validateModality(node);
+		}
+		validateAccess(
+			node,
+			ns.getTable(),
+			SqlAccessEnum.SELECT);
+	}
+
+	/**
+	 * Validates a namespace.
+	 *
+	 * @param namespace Namespace
+	 * @param targetRowType Desired row type, must not be null, may be the data
+	 *                      type 'unknown'.
+	 */
+	protected void validateNamespace(final SqlValidatorNamespace namespace,
+		RelDataType targetRowType) {
+		namespace.validate(targetRowType);
+		if (namespace.getNode() != null) {
+			setValidatedNodeType(namespace.getNode(), namespace.getType());
+		}
+	}
+
+	@VisibleForTesting
+	public SqlValidatorScope getEmptyScope() {
+		return new EmptyScope(this);
+	}
+
+	public SqlValidatorScope getCursorScope(SqlSelect select) {
+		return cursorScopes.get(select);
+	}
+
+	public SqlValidatorScope getWhereScope(SqlSelect select) {
+		return whereScopes.get(select);
+	}
+
+	public SqlValidatorScope getSelectScope(SqlSelect select) {
+		return selectScopes.get(select);
+	}
+
+	public SelectScope getRawSelectScope(SqlSelect select) {
+		SqlValidatorScope scope = getSelectScope(select);
+		if (scope instanceof AggregatingSelectScope) {
+			scope = ((AggregatingSelectScope) scope).getParent();
+		}
+		return (SelectScope) scope;
+	}
+
+	public SqlValidatorScope getHavingScope(SqlSelect select) {
+		// Yes, it's the same as getSelectScope
+		return selectScopes.get(select);
+	}
+
+	public SqlValidatorScope getGroupScope(SqlSelect select) {
+		// Yes, it's the same as getWhereScope
+		return groupByScopes.get(select);
+	}
+
+	public SqlValidatorScope getFromScope(SqlSelect select) {
+		return scopes.get(select);
+	}
+
+	public SqlValidatorScope getOrderScope(SqlSelect select) {
+		return orderScopes.get(select);
+	}
+
+	public SqlValidatorScope getMatchRecognizeScope(SqlMatchRecognize node) {
+		return scopes.get(node);
+	}
+
+	public SqlValidatorScope getJoinScope(SqlNode node) {
+		return scopes.get(stripAs(node));
+	}
+
+	public SqlValidatorScope getOverScope(SqlNode node) {
+		return scopes.get(node);
+	}
+
+	private SqlValidatorNamespace getNamespace(SqlNode node,
+		SqlValidatorScope scope) {
+		if (node instanceof SqlIdentifier && scope instanceof DelegatingScope) {
+			final SqlIdentifier id = (SqlIdentifier) node;
+			final DelegatingScope idScope = (DelegatingScope) ((DelegatingScope) scope).getParent();
+			return getNamespace(id, idScope);
+		} else if (node instanceof SqlCall) {
+			// Handle extended identifiers.
+			final SqlCall call = (SqlCall) node;
+			switch (call.getOperator().getKind()) {
+				case EXTEND:
+					final SqlIdentifier id = (SqlIdentifier) call.getOperandList().get(0);
+					final DelegatingScope idScope = (DelegatingScope) scope;
+					return getNamespace(id, idScope);
+				case AS:
+					final SqlNode nested = call.getOperandList().get(0);
+					switch (nested.getKind()) {
+						case EXTEND:
+							return getNamespace(nested, scope);
+					}
+					break;
+			}
+		}
+		return getNamespace(node);
+	}
+
+	private SqlValidatorNamespace getNamespace(SqlIdentifier id, DelegatingScope scope) {
+		if (id.isSimple()) {
+			final SqlNameMatcher nameMatcher = catalogReader.nameMatcher();
+			final SqlValidatorScope.ResolvedImpl resolved =
+				new SqlValidatorScope.ResolvedImpl();
+			scope.resolve(id.names, nameMatcher, false, resolved);
+			if (resolved.count() == 1) {
+				return resolved.only().namespace;
+			}
+		}
+		return getNamespace(id);
+	}
+
+	public SqlValidatorNamespace getNamespace(SqlNode node) {
+		switch (node.getKind()) {
+			case AS:
+
+				// AS has a namespace if it has a column list 'AS t (c1, c2, ...)'
+				final SqlValidatorNamespace ns = namespaces.get(node);
+				if (ns != null) {
+					return ns;
+				}
+				// fall through
+			case OVER:
+			case COLLECTION_TABLE:
+			case ORDER_BY:
+			case TABLESAMPLE:
+				return getNamespace(((SqlCall) node).operand(0));
+			default:
+				return namespaces.get(node);
+		}
+	}
+
+	private void handleOffsetFetch(SqlNode offset, SqlNode fetch) {
+		if (offset instanceof SqlDynamicParam) {
+			setValidatedNodeType(offset,
+				typeFactory.createSqlType(SqlTypeName.INTEGER));
+		}
+		if (fetch instanceof SqlDynamicParam) {
+			setValidatedNodeType(fetch,
+				typeFactory.createSqlType(SqlTypeName.INTEGER));
+		}
+	}
+
+	/**
+	 * Performs expression rewrites which are always used unconditionally. These
+	 * rewrites massage the expression tree into a standard form so that the
+	 * rest of the validation logic can be simpler.
+	 *
+	 * @param node      expression to be rewritten
+	 * @param underFrom whether node appears directly under a FROM clause
+	 * @return rewritten expression
+	 */
+	protected SqlNode performUnconditionalRewrites(
+		SqlNode node,
+		boolean underFrom) {
+		if (node == null) {
+			return node;
+		}
+
+		SqlNode newOperand;
+
+		// first transform operands and invoke generic call rewrite
+		if (node instanceof SqlCall) {
+			if (node instanceof SqlMerge) {
+				validatingSqlMerge = true;
+			}
+			SqlCall call = (SqlCall) node;
+			final SqlKind kind = call.getKind();
+			final List<SqlNode> operands = call.getOperandList();
+			for (int i = 0; i < operands.size(); i++) {
+				SqlNode operand = operands.get(i);
+				boolean childUnderFrom;
+				if (kind == SqlKind.SELECT) {
+					childUnderFrom = i == SqlSelect.FROM_OPERAND;
+				} else if (kind == SqlKind.AS && (i == 0)) {
+					// for an aliased expression, it is under FROM if
+					// the AS expression is under FROM
+					childUnderFrom = underFrom;
+				} else {
+					childUnderFrom = false;
+				}
+				newOperand =
+					performUnconditionalRewrites(operand, childUnderFrom);
+				if (newOperand != null && newOperand != operand) {
+					call.setOperand(i, newOperand);
+				}
+			}
+
+			if (call.getOperator() instanceof SqlUnresolvedFunction) {
+				assert call instanceof SqlBasicCall;
+				final SqlUnresolvedFunction function =
+					(SqlUnresolvedFunction) call.getOperator();
+				// This function hasn't been resolved yet.  Perform
+				// a half-hearted resolution now in case it's a
+				// builtin function requiring special casing.  If it's
+				// not, we'll handle it later during overload resolution.
+				final List<SqlOperator> overloads = new ArrayList<>();
+				opTab.lookupOperatorOverloads(function.getNameAsId(),
+					function.getFunctionType(), SqlSyntax.FUNCTION, overloads);
+				if (overloads.size() == 1) {
+					((SqlBasicCall) call).setOperator(overloads.get(0));
+				}
+			}
+			if (rewriteCalls) {
+				node = call.getOperator().rewriteCall(this, call);
+			}
+		} else if (node instanceof SqlNodeList) {
+			SqlNodeList list = (SqlNodeList) node;
+			for (int i = 0, count = list.size(); i < count; i++) {
+				SqlNode operand = list.get(i);
+				newOperand =
+					performUnconditionalRewrites(
+						operand,
+						false);
+				if (newOperand != null) {
+					list.getList().set(i, newOperand);
+				}
+			}
+		}
+
+		// now transform node itself
+		final SqlKind kind = node.getKind();
+		switch (kind) {
+			case VALUES:
+				// CHECKSTYLE: IGNORE 1
+				if (underFrom || true) {
+					// leave FROM (VALUES(...)) [ AS alias ] clauses alone,
+					// otherwise they grow cancerously if this rewrite is invoked
+					// over and over
+					return node;
+				} else {
+					final SqlNodeList selectList =
+						new SqlNodeList(SqlParserPos.ZERO);
+					selectList.add(SqlIdentifier.star(SqlParserPos.ZERO));
+					return new SqlSelect(node.getParserPosition(), null, selectList, node,
+						null, null, null, null, null, null, null);
+				}
+
+			case ORDER_BY: {
+				SqlOrderBy orderBy = (SqlOrderBy) node;
+				handleOffsetFetch(orderBy.offset, orderBy.fetch);
+				if (orderBy.query instanceof SqlSelect) {
+					SqlSelect select = (SqlSelect) orderBy.query;
+
+					// Don't clobber existing ORDER BY.  It may be needed for
+					// an order-sensitive function like RANK.
+					if (select.getOrderList() == null) {
+						// push ORDER BY into existing select
+						select.setOrderBy(orderBy.orderList);
+						select.setOffset(orderBy.offset);
+						select.setFetch(orderBy.fetch);
+						return select;
+					}
+				}
+				if (orderBy.query instanceof SqlWith
+					&& ((SqlWith) orderBy.query).body instanceof SqlSelect) {
+					SqlWith with = (SqlWith) orderBy.query;
+					SqlSelect select = (SqlSelect) with.body;
+
+					// Don't clobber existing ORDER BY.  It may be needed for
+					// an order-sensitive function like RANK.
+					if (select.getOrderList() == null) {
+						// push ORDER BY into existing select
+						select.setOrderBy(orderBy.orderList);
+						select.setOffset(orderBy.offset);
+						select.setFetch(orderBy.fetch);
+						return with;
+					}
+				}
+				final SqlNodeList selectList = new SqlNodeList(SqlParserPos.ZERO);
+				selectList.add(SqlIdentifier.star(SqlParserPos.ZERO));
+				final SqlNodeList orderList;
+				if (getInnerSelect(node) != null && isAggregate(getInnerSelect(node))) {
+					orderList = SqlNode.clone(orderBy.orderList);
+					// We assume that ORDER BY item does not have ASC etc.
+					// We assume that ORDER BY item is present in SELECT list.
+					for (int i = 0; i < orderList.size(); i++) {
+						SqlNode sqlNode = orderList.get(i);
+						SqlNodeList selectList2 = getInnerSelect(node).getSelectList();
+						for (Ord<SqlNode> sel : Ord.zip(selectList2)) {
+							if (stripAs(sel.e).equalsDeep(sqlNode, Litmus.IGNORE)) {
+								orderList.set(i,
+									SqlLiteral.createExactNumeric(Integer.toString(sel.i + 1),
+										SqlParserPos.ZERO));
+							}
+						}
+					}
+				} else {
+					orderList = orderBy.orderList;
+				}
+				return new SqlSelect(SqlParserPos.ZERO, null, selectList, orderBy.query,
+					null, null, null, null, orderList, orderBy.offset,
+					orderBy.fetch);
+			}
+
+			case EXPLICIT_TABLE: {
+				// (TABLE t) is equivalent to (SELECT * FROM t)
+				SqlCall call = (SqlCall) node;
+				final SqlNodeList selectList = new SqlNodeList(SqlParserPos.ZERO);
+				selectList.add(SqlIdentifier.star(SqlParserPos.ZERO));
+				return new SqlSelect(SqlParserPos.ZERO, null, selectList, call.operand(0),
+					null, null, null, null, null, null, null);
+			}
+
+			case DELETE: {
+				SqlDelete call = (SqlDelete) node;
+				SqlSelect select = createSourceSelectForDelete(call);
+				call.setSourceSelect(select);
+				break;
+			}
+
+			case UPDATE: {
+				SqlUpdate call = (SqlUpdate) node;
+				SqlSelect select = createSourceSelectForUpdate(call);
+				call.setSourceSelect(select);
+
+				// See if we're supposed to rewrite UPDATE to MERGE
+				// (unless this is the UPDATE clause of a MERGE,
+				// in which case leave it alone).
+				if (!validatingSqlMerge) {
+					SqlNode selfJoinSrcExpr =
+						getSelfJoinExprForUpdate(
+							call.getTargetTable(),
+							UPDATE_SRC_ALIAS);
+					if (selfJoinSrcExpr != null) {
+						node = rewriteUpdateToMerge(call, selfJoinSrcExpr);
+					}
+				}
+				break;
+			}
+
+			case MERGE: {
+				SqlMerge call = (SqlMerge) node;
+				rewriteMerge(call);
+				break;
+			}
+		}
+		return node;
+	}
+
+	private SqlSelect getInnerSelect(SqlNode node) {
+		for (;;) {
+			if (node instanceof SqlSelect) {
+				return (SqlSelect) node;
+			} else if (node instanceof SqlOrderBy) {
+				node = ((SqlOrderBy) node).query;
+			} else if (node instanceof SqlWith) {
+				node = ((SqlWith) node).body;
+			} else {
+				return null;
+			}
+		}
+	}
+
+	private void rewriteMerge(SqlMerge call) {
+		SqlNodeList selectList;
+		SqlUpdate updateStmt = call.getUpdateCall();
+		if (updateStmt != null) {
+			// if we have an update statement, just clone the select list
+			// from the update statement's source since it's the same as
+			// what we want for the select list of the merge source -- '*'
+			// followed by the update set expressions
+			selectList = SqlNode.clone(updateStmt.getSourceSelect().getSelectList());
+		} else {
+			// otherwise, just use select *
+			selectList = new SqlNodeList(SqlParserPos.ZERO);
+			selectList.add(SqlIdentifier.star(SqlParserPos.ZERO));
+		}
+		SqlNode targetTable = call.getTargetTable();
+		if (call.getAlias() != null) {
+			targetTable =
+				SqlValidatorUtil.addAlias(
+					targetTable,
+					call.getAlias().getSimple());
+		}
+
+		// Provided there is an insert substatement, the source select for
+		// the merge is a left outer join between the source in the USING
+		// clause and the target table; otherwise, the join is just an
+		// inner join.  Need to clone the source table reference in order
+		// for validation to work
+		SqlNode sourceTableRef = call.getSourceTableRef();
+		SqlInsert insertCall = call.getInsertCall();
+		JoinType joinType = (insertCall == null) ? JoinType.INNER : JoinType.LEFT;
+		final SqlNode leftJoinTerm = SqlNode.clone(sourceTableRef);
+		SqlNode outerJoin =
+			new SqlJoin(SqlParserPos.ZERO,
+				leftJoinTerm,
+				SqlLiteral.createBoolean(false, SqlParserPos.ZERO),
+				joinType.symbol(SqlParserPos.ZERO),
+				targetTable,
+				JoinConditionType.ON.symbol(SqlParserPos.ZERO),
+				call.getCondition());
+		SqlSelect select =
+			new SqlSelect(SqlParserPos.ZERO, null, selectList, outerJoin, null,
+				null, null, null, null, null, null);
+		call.setSourceSelect(select);
+
+		// Source for the insert call is a select of the source table
+		// reference with the select list being the value expressions;
+		// note that the values clause has already been converted to a
+		// select on the values row constructor; so we need to extract
+		// that via the from clause on the select
+		if (insertCall != null) {
+			SqlCall valuesCall = (SqlCall) insertCall.getSource();
+			SqlCall rowCall = valuesCall.operand(0);
+			selectList =
+				new SqlNodeList(
+					rowCall.getOperandList(),
+					SqlParserPos.ZERO);
+			final SqlNode insertSource = SqlNode.clone(sourceTableRef);
+			select =
+				new SqlSelect(SqlParserPos.ZERO, null, selectList, insertSource, null,
+					null, null, null, null, null, null);
+			insertCall.setSource(select);
+		}
+	}
+
+	private SqlNode rewriteUpdateToMerge(
+		SqlUpdate updateCall,
+		SqlNode selfJoinSrcExpr) {
+		// Make sure target has an alias.
+		if (updateCall.getAlias() == null) {
+			updateCall.setAlias(
+				new SqlIdentifier(UPDATE_TGT_ALIAS, SqlParserPos.ZERO));
+		}
+		SqlNode selfJoinTgtExpr =
+			getSelfJoinExprForUpdate(
+				updateCall.getTargetTable(),
+				updateCall.getAlias().getSimple());
+		assert selfJoinTgtExpr != null;
+
+		// Create join condition between source and target exprs,
+		// creating a conjunction with the user-level WHERE
+		// clause if one was supplied
+		SqlNode condition = updateCall.getCondition();
+		SqlNode selfJoinCond =
+			SqlStdOperatorTable.EQUALS.createCall(
+				SqlParserPos.ZERO,
+				selfJoinSrcExpr,
+				selfJoinTgtExpr);
+		if (condition == null) {
+			condition = selfJoinCond;
+		} else {
+			condition =
+				SqlStdOperatorTable.AND.createCall(
+					SqlParserPos.ZERO,
+					selfJoinCond,
+					condition);
+		}
+		SqlNode target =
+			updateCall.getTargetTable().clone(SqlParserPos.ZERO);
+
+		// For the source, we need to anonymize the fields, so
+		// that for a statement like UPDATE T SET I = I + 1,
+		// there's no ambiguity for the "I" in "I + 1";
+		// this is OK because the source and target have
+		// identical values due to the self-join.
+		// Note that we anonymize the source rather than the
+		// target because downstream, the optimizer rules
+		// don't want to see any projection on top of the target.
+		IdentifierNamespace ns =
+			new IdentifierNamespace(this, target, null, null);
+		RelDataType rowType = ns.getRowType();
+		SqlNode source = updateCall.getTargetTable().clone(SqlParserPos.ZERO);
+		final SqlNodeList selectList = new SqlNodeList(SqlParserPos.ZERO);
+		int i = 1;
+		for (RelDataTypeField field : rowType.getFieldList()) {
+			SqlIdentifier col =
+				new SqlIdentifier(
+					field.getName(),
+					SqlParserPos.ZERO);
+			selectList.add(
+				SqlValidatorUtil.addAlias(col, UPDATE_ANON_PREFIX + i));
+			++i;
+		}
+		source =
+			new SqlSelect(SqlParserPos.ZERO, null, selectList, source, null, null,
+				null, null, null, null, null);
+		source = SqlValidatorUtil.addAlias(source, UPDATE_SRC_ALIAS);
+		SqlMerge mergeCall =
+			new SqlMerge(updateCall.getParserPosition(), target, condition, source,
+				updateCall, null, null, updateCall.getAlias());
+		rewriteMerge(mergeCall);
+		return mergeCall;
+	}
+
+	/**
+	 * Allows a subclass to provide information about how to convert an UPDATE
+	 * into a MERGE via self-join. If this method returns null, then no such
+	 * conversion takes place. Otherwise, this method should return a suitable
+	 * unique identifier expression for the given table.
+	 *
+	 * @param table identifier for table being updated
+	 * @param alias alias to use for qualifying columns in expression, or null
+	 *              for unqualified references; if this is equal to
+	 *              {@value #UPDATE_SRC_ALIAS}, then column references have been
+	 *              anonymized to "SYS$ANONx", where x is the 1-based column
+	 *              number.
+	 * @return expression for unique identifier, or null to prevent conversion
+	 */
+	protected SqlNode getSelfJoinExprForUpdate(
+		SqlNode table,
+		String alias) {
+		return null;
+	}
+
+	/**
+	 * Creates the SELECT statement that putatively feeds rows into an UPDATE
+	 * statement to be updated.
+	 *
+	 * @param call Call to the UPDATE operator
+	 * @return select statement
+	 */
+	protected SqlSelect createSourceSelectForUpdate(SqlUpdate call) {
+		final SqlNodeList selectList = new SqlNodeList(SqlParserPos.ZERO);
+		selectList.add(SqlIdentifier.star(SqlParserPos.ZERO));
+		int ordinal = 0;
+		for (SqlNode exp : call.getSourceExpressionList()) {
+			// Force unique aliases to avoid a duplicate for Y with
+			// SET X=Y
+			String alias = SqlUtil.deriveAliasFromOrdinal(ordinal);
+			selectList.add(SqlValidatorUtil.addAlias(exp, alias));
+			++ordinal;
+		}
+		SqlNode sourceTable = call.getTargetTable();
+		if (call.getAlias() != null) {
+			sourceTable =
+				SqlValidatorUtil.addAlias(
+					sourceTable,
+					call.getAlias().getSimple());
+		}
+		return new SqlSelect(SqlParserPos.ZERO, null, selectList, sourceTable,
+			call.getCondition(), null, null, null, null, null, null);
+	}
+
+	/**
+	 * Creates the SELECT statement that putatively feeds rows into a DELETE
+	 * statement to be deleted.
+	 *
+	 * @param call Call to the DELETE operator
+	 * @return select statement
+	 */
+	protected SqlSelect createSourceSelectForDelete(SqlDelete call) {
+		final SqlNodeList selectList = new SqlNodeList(SqlParserPos.ZERO);
+		selectList.add(SqlIdentifier.star(SqlParserPos.ZERO));
+		SqlNode sourceTable = call.getTargetTable();
+		if (call.getAlias() != null) {
+			sourceTable =
+				SqlValidatorUtil.addAlias(
+					sourceTable,
+					call.getAlias().getSimple());
+		}
+		return new SqlSelect(SqlParserPos.ZERO, null, selectList, sourceTable,
+			call.getCondition(), null, null, null, null, null, null);
+	}
+
+	/**
+	 * Returns null if there is no common type. E.g. if the rows have a
+	 * different number of columns.
+	 */
+	RelDataType getTableConstructorRowType(
+		SqlCall values,
+		SqlValidatorScope scope) {
+		final List<SqlNode> rows = values.getOperandList();
+		assert rows.size() >= 1;
+		final List<RelDataType> rowTypes = new ArrayList<>();
+		for (final SqlNode row : rows) {
+			assert row.getKind() == SqlKind.ROW;
+			SqlCall rowConstructor = (SqlCall) row;
+
+			// REVIEW jvs 10-Sept-2003: Once we support single-row queries as
+			// rows, need to infer aliases from there.
+			final List<String> aliasList = new ArrayList<>();
+			final List<RelDataType> typeList = new ArrayList<>();
+			for (Ord<SqlNode> column : Ord.zip(rowConstructor.getOperandList())) {
+				final String alias = deriveAlias(column.e, column.i);
+				aliasList.add(alias);
+				final RelDataType type = deriveType(scope, column.e);
+				typeList.add(type);
+			}
+			rowTypes.add(typeFactory.createStructType(typeList, aliasList));
+		}
+		if (rows.size() == 1) {
+			// TODO jvs 10-Oct-2005:  get rid of this workaround once
+			// leastRestrictive can handle all cases
+			return rowTypes.get(0);
+		}
+		return typeFactory.leastRestrictive(rowTypes);
+	}
+
+	public RelDataType getValidatedNodeType(SqlNode node) {
+		RelDataType type = getValidatedNodeTypeIfKnown(node);
+		if (type == null) {
+			throw Util.needToImplement(node);
+		} else {
+			return type;
+		}
+	}
+
+	public RelDataType getValidatedNodeTypeIfKnown(SqlNode node) {
+		final RelDataType type = nodeToTypeMap.get(node);
+		if (type != null) {
+			return type;
+		}
+		final SqlValidatorNamespace ns = getNamespace(node);
+		if (ns != null) {
+			return ns.getType();
+		}
+		final SqlNode original = originalExprs.get(node);
+		if (original != null && original != node) {
+			return getValidatedNodeType(original);
+		}
+		if (node instanceof SqlIdentifier) {
+			return getCatalogReader().getNamedType((SqlIdentifier) node);
+		}
+		return null;
+	}
+
+	/**
+	 * Saves the type of a {@link SqlNode}, now that it has been validated.
+	 *
+	 * <p>Unlike the base class method, this method is not deprecated.
+	 * It is available from within Calcite, but is not part of the public API.
+	 *
+	 * @param node A SQL parse tree node, never null
+	 * @param type Its type; must not be null
+	 */
+	@SuppressWarnings("deprecation")
+	public final void setValidatedNodeType(SqlNode node, RelDataType type) {
+		Objects.requireNonNull(type);
+		Objects.requireNonNull(node);
+		if (type.equals(unknownType)) {
+			// don't set anything until we know what it is, and don't overwrite
+			// a known type with the unknown type
+			return;
+		}
+		nodeToTypeMap.put(node, type);
+	}
+
+	public void removeValidatedNodeType(SqlNode node) {
+		nodeToTypeMap.remove(node);
+	}
+
+	public RelDataType deriveType(
+		SqlValidatorScope scope,
+		SqlNode expr) {
+		Objects.requireNonNull(scope);
+		Objects.requireNonNull(expr);
+
+		// if we already know the type, no need to re-derive
+		RelDataType type = nodeToTypeMap.get(expr);
+		if (type != null) {
+			return type;
+		}
+		final SqlValidatorNamespace ns = getNamespace(expr);
+		if (ns != null) {
+			return ns.getType();
+		}
+		type = deriveTypeImpl(scope, expr);
+		Preconditions.checkArgument(
+			type != null,
+			"SqlValidator.deriveTypeInternal returned null");
+		setValidatedNodeType(expr, type);
+		return type;
+	}
+
+	/**
+	 * Derives the type of a node, never null.
+	 */
+	RelDataType deriveTypeImpl(
+		SqlValidatorScope scope,
+		SqlNode operand) {
+		DeriveTypeVisitor v = new DeriveTypeVisitor(scope);
+		final RelDataType type = operand.accept(v);
+		return Objects.requireNonNull(scope.nullifyType(operand, type));
+	}
+
+	public RelDataType deriveConstructorType(
+		SqlValidatorScope scope,
+		SqlCall call,
+		SqlFunction unresolvedConstructor,
+		SqlFunction resolvedConstructor,
+		List<RelDataType> argTypes) {
+		SqlIdentifier sqlIdentifier = unresolvedConstructor.getSqlIdentifier();
+		assert sqlIdentifier != null;
+		RelDataType type = catalogReader.getNamedType(sqlIdentifier);
+		if (type == null) {
+			// TODO jvs 12-Feb-2005:  proper type name formatting
+			throw newValidationError(sqlIdentifier,
+				RESOURCE.unknownDatatypeName(sqlIdentifier.toString()));
+		}
+
+		if (resolvedConstructor == null) {
+			if (call.operandCount() > 0) {
+				// This is not a default constructor invocation, and
+				// no user-defined constructor could be found
+				throw handleUnresolvedFunction(call, unresolvedConstructor, argTypes,
+					null);
+			}
+		} else {
+			SqlCall testCall =
+				resolvedConstructor.createCall(
+					call.getParserPosition(),
+					call.getOperandList());
+			RelDataType returnType =
+				resolvedConstructor.validateOperands(
+					this,
+					scope,
+					testCall);
+			assert type == returnType;
+		}
+
+		if (shouldExpandIdentifiers()) {
+			if (resolvedConstructor != null) {
+				((SqlBasicCall) call).setOperator(resolvedConstructor);
+			} else {
+				// fake a fully-qualified call to the default constructor
+				((SqlBasicCall) call).setOperator(
+					new SqlFunction(
+						type.getSqlIdentifier(),
+						ReturnTypes.explicit(type),
+						null,
+						null,
+						null,
+						SqlFunctionCategory.USER_DEFINED_CONSTRUCTOR));
+			}
+		}
+		return type;
+	}
+
+	public CalciteException handleUnresolvedFunction(SqlCall call,
+		SqlFunction unresolvedFunction, List<RelDataType> argTypes,
+		List<String> argNames) {
+		// For builtins, we can give a better error message
+		final List<SqlOperator> overloads = new ArrayList<>();
+		opTab.lookupOperatorOverloads(unresolvedFunction.getNameAsId(), null,
+			SqlSyntax.FUNCTION, overloads);
+		if (overloads.size() == 1) {
+			SqlFunction fun = (SqlFunction) overloads.get(0);
+			if ((fun.getSqlIdentifier() == null)
+				&& (fun.getSyntax() != SqlSyntax.FUNCTION_ID)) {
+				final int expectedArgCount =
+					fun.getOperandCountRange().getMin();
+				throw newValidationError(call,
+					RESOURCE.invalidArgCount(call.getOperator().getName(),
+						expectedArgCount));
+			}
+		}
+
+		AssignableOperandTypeChecker typeChecking =
+			new AssignableOperandTypeChecker(argTypes, argNames);
+		String signature =
+			typeChecking.getAllowedSignatures(
+				unresolvedFunction,
+				unresolvedFunction.getName());
+		throw newValidationError(call,
+			RESOURCE.validatorUnknownFunction(signature));
+	}
+
+	protected void inferUnknownTypes(
+		RelDataType inferredType,
+		SqlValidatorScope scope,
+		SqlNode node) {
+		final SqlValidatorScope newScope = scopes.get(node);
+		if (newScope != null) {
+			scope = newScope;
+		}
+		boolean isNullLiteral = SqlUtil.isNullLiteral(node, false);
+		if ((node instanceof SqlDynamicParam) || isNullLiteral) {
+			if (inferredType.equals(unknownType)) {
+				if (isNullLiteral) {
+					throw newValidationError(node, RESOURCE.nullIllegal());
+				} else {
+					throw newValidationError(node, RESOURCE.dynamicParamIllegal());
+				}
+			}
+
+			// REVIEW:  should dynamic parameter types always be nullable?
+			RelDataType newInferredType =
+				typeFactory.createTypeWithNullability(inferredType, true);
+			if (SqlTypeUtil.inCharFamily(inferredType)) {
+				newInferredType =
+					typeFactory.createTypeWithCharsetAndCollation(
+						newInferredType,
+						inferredType.getCharset(),
+						inferredType.getCollation());
+			}
+			setValidatedNodeType(node, newInferredType);
+		} else if (node instanceof SqlNodeList) {
+			SqlNodeList nodeList = (SqlNodeList) node;
+			if (inferredType.isStruct()) {
+				if (inferredType.getFieldCount() != nodeList.size()) {
+					// this can happen when we're validating an INSERT
+					// where the source and target degrees are different;
+					// bust out, and the error will be detected higher up
+					return;
+				}
+			}
+			int i = 0;
+			for (SqlNode child : nodeList) {
+				RelDataType type;
+				if (inferredType.isStruct()) {
+					type = inferredType.getFieldList().get(i).getType();
+					++i;
+				} else {
+					type = inferredType;
+				}
+				inferUnknownTypes(type, scope, child);
+			}
+		} else if (node instanceof SqlCase) {
+			final SqlCase caseCall = (SqlCase) node;
+
+			final RelDataType whenType =
+				caseCall.getValueOperand() == null ? booleanType : unknownType;
+			for (SqlNode sqlNode : caseCall.getWhenOperands().getList()) {
+				inferUnknownTypes(whenType, scope, sqlNode);
+			}
+			RelDataType returnType = deriveType(scope, node);
+			for (SqlNode sqlNode : caseCall.getThenOperands().getList()) {
+				inferUnknownTypes(returnType, scope, sqlNode);
+			}
+
+			if (!SqlUtil.isNullLiteral(caseCall.getElseOperand(), false)) {
+				inferUnknownTypes(
+					returnType,
+					scope,
+					caseCall.getElseOperand());
+			} else {
+				setValidatedNodeType(caseCall.getElseOperand(), returnType);
+			}
+		} else if (node instanceof SqlCall) {
+			final SqlCall call = (SqlCall) node;
+			final SqlOperandTypeInference operandTypeInference =
+				call.getOperator().getOperandTypeInference();
+			final SqlCallBinding callBinding = new SqlCallBinding(this, scope, call);
+			final List<SqlNode> operands = callBinding.operands();
+			final RelDataType[] operandTypes = new RelDataType[operands.size()];
+			if (operandTypeInference == null) {
+				// TODO:  eventually should assert(operandTypeInference != null)
+				// instead; for now just eat it
+				Arrays.fill(operandTypes, unknownType);
+			} else {
+				operandTypeInference.inferOperandTypes(
+					callBinding,
+					inferredType,
+					operandTypes);
+			}
+			for (int i = 0; i < operands.size(); ++i) {
+				inferUnknownTypes(operandTypes[i], scope, operands.get(i));
+			}
+		}
+	}
+
+	/**
+	 * Adds an expression to a select list, ensuring that its alias does not
+	 * clash with any existing expressions on the list.
+	 */
+	protected void addToSelectList(
+		List<SqlNode> list,
+		Set<String> aliases,
+		List<Map.Entry<String, RelDataType>> fieldList,
+		SqlNode exp,
+		SqlValidatorScope scope,
+		final boolean includeSystemVars) {
+		String alias = SqlValidatorUtil.getAlias(exp, -1);
+		String uniqueAlias =
+			SqlValidatorUtil.uniquify(
+				alias, aliases, SqlValidatorUtil.EXPR_SUGGESTER);
+		if (!alias.equals(uniqueAlias)) {
+			exp = SqlValidatorUtil.addAlias(exp, uniqueAlias);
+		}
+		fieldList.add(Pair.of(uniqueAlias, deriveType(scope, exp)));
+		list.add(exp);
+	}
+
+	public String deriveAlias(
+		SqlNode node,
+		int ordinal) {
+		return SqlValidatorUtil.getAlias(node, ordinal);
+	}
+
+	// implement SqlValidator
+	public void setIdentifierExpansion(boolean expandIdentifiers) {
+		this.expandIdentifiers = expandIdentifiers;
+	}
+
+	// implement SqlValidator
+	public void setColumnReferenceExpansion(
+		boolean expandColumnReferences) {
+		this.expandColumnReferences = expandColumnReferences;
+	}
+
+	// implement SqlValidator
+	public boolean getColumnReferenceExpansion() {
+		return expandColumnReferences;
+	}
+
+	public void setDefaultNullCollation(NullCollation nullCollation) {
+		this.nullCollation = Objects.requireNonNull(nullCollation);
+	}
+
+	public NullCollation getDefaultNullCollation() {
+		return nullCollation;
+	}
+
+	// implement SqlValidator
+	public void setCallRewrite(boolean rewriteCalls) {
+		this.rewriteCalls = rewriteCalls;
+	}
+
+	public boolean shouldExpandIdentifiers() {
+		return expandIdentifiers;
+	}
+
+	protected boolean shouldAllowIntermediateOrderBy() {
+		return true;
+	}
+
+	private void registerMatchRecognize(
+		SqlValidatorScope parentScope,
+		SqlValidatorScope usingScope,
+		SqlMatchRecognize call,
+		SqlNode enclosingNode,
+		String alias,
+		boolean forceNullable) {
+
+		final MatchRecognizeNamespace matchRecognizeNamespace =
+			createMatchRecognizeNameSpace(call, enclosingNode);
+		registerNamespace(usingScope, alias, matchRecognizeNamespace, forceNullable);
+
+		final MatchRecognizeScope matchRecognizeScope =
+			new MatchRecognizeScope(parentScope, call);
+		scopes.put(call, matchRecognizeScope);
+
+		// parse input query
+		SqlNode expr = call.getTableRef();
+		SqlNode newExpr = registerFrom(usingScope, matchRecognizeScope, true, expr,
+			expr, null, null, forceNullable, false);
+		if (expr != newExpr) {
+			call.setOperand(0, newExpr);
+		}
+	}
+
+	protected MatchRecognizeNamespace createMatchRecognizeNameSpace(
+		SqlMatchRecognize call,
+		SqlNode enclosingNode) {
+		return new MatchRecognizeNamespace(this, call, enclosingNode);
+	}
+
+	/**
+	 * Registers a new namespace, and adds it as a child of its parent scope.
+	 * Derived class can override this method to tinker with namespaces as they
+	 * are created.
+	 *
+	 * @param usingScope    Parent scope (which will want to look for things in
+	 *                      this namespace)
+	 * @param alias         Alias by which parent will refer to this namespace
+	 * @param ns            Namespace
+	 * @param forceNullable Whether to force the type of namespace to be nullable
+	 */
+	protected void registerNamespace(
+		SqlValidatorScope usingScope,
+		String alias,
+		SqlValidatorNamespace ns,
+		boolean forceNullable) {
+		namespaces.put(ns.getNode(), ns);
+		if (usingScope != null) {
+			usingScope.addChild(ns, alias, forceNullable);
+		}
+	}
+
+	/**
+	 * Registers scopes and namespaces implied a relational expression in the
+	 * FROM clause.
+	 *
+	 * <p>{@code parentScope} and {@code usingScope} are often the same. They
+	 * differ when the namespace are not visible within the parent. (Example
+	 * needed.)
+	 *
+	 * <p>Likewise, {@code enclosingNode} and {@code node} are often the same.
+	 * {@code enclosingNode} is the topmost node within the FROM clause, from
+	 * which any decorations like an alias (<code>AS alias</code>) or a table
+	 * sample clause are stripped away to get {@code node}. Both are recorded in
+	 * the namespace.
+	 *
+	 * @param parentScope   Parent scope which this scope turns to in order to
+	 *                      resolve objects
+	 * @param usingScope    Scope whose child list this scope should add itself to
+	 * @param register      Whether to register this scope as a child of
+	 *                      {@code usingScope}
+	 * @param node          Node which namespace is based on
+	 * @param enclosingNode Outermost node for namespace, including decorations
+	 *                      such as alias and sample clause
+	 * @param alias         Alias
+	 * @param extendList    Definitions of extended columns
+	 * @param forceNullable Whether to force the type of namespace to be
+	 *                      nullable because it is in an outer join
+	 * @param lateral       Whether LATERAL is specified, so that items to the
+	 *                      left of this in the JOIN tree are visible in the
+	 *                      scope
+	 * @return registered node, usually the same as {@code node}
+	 */
+	private SqlNode registerFrom(
+		SqlValidatorScope parentScope,
+		SqlValidatorScope usingScope,
+		boolean register,
+		final SqlNode node,
+		SqlNode enclosingNode,
+		String alias,
+		SqlNodeList extendList,
+		boolean forceNullable,
+		final boolean lateral) {
+		final SqlKind kind = node.getKind();
+
+		SqlNode expr;
+		SqlNode newExpr;
+
+		// Add an alias if necessary.
+		SqlNode newNode = node;
+		if (alias == null) {
+			switch (kind) {
+				case IDENTIFIER:
+				case OVER:
+					alias = deriveAlias(node, -1);
+					if (alias == null) {
+						alias = deriveAlias(node, nextGeneratedId++);
+					}
+					if (shouldExpandIdentifiers()) {
+						newNode = SqlValidatorUtil.addAlias(node, alias);
+					}
+					break;
+
+				case SELECT:
+				case UNION:
+				case INTERSECT:
+				case EXCEPT:
+				case VALUES:
+				case UNNEST:
+				case OTHER_FUNCTION:
+				case COLLECTION_TABLE:
+				case MATCH_RECOGNIZE:
+
+					// give this anonymous construct a name since later
+					// query processing stages rely on it
+					alias = deriveAlias(node, nextGeneratedId++);
+					if (shouldExpandIdentifiers()) {
+						// Since we're expanding identifiers, we should make the
+						// aliases explicit too, otherwise the expanded query
+						// will not be consistent if we convert back to SQL, e.g.
+						// "select EXPR$1.EXPR$2 from values (1)".
+						newNode = SqlValidatorUtil.addAlias(node, alias);
+					}
+					break;
+			}
+		}
+
+		if (lateral) {
+			SqlValidatorScope s = usingScope;
+			while (s instanceof JoinScope) {
+				s = ((JoinScope) s).getUsingScope();
+			}
+			final SqlNode node2 = s != null ? s.getNode() : node;
+			final TableScope tableScope = new TableScope(parentScope, node2);
+			if (usingScope instanceof ListScope) {
+				for (ScopeChild child : ((ListScope) usingScope).children) {
+					tableScope.addChild(child.namespace, child.name, child.nullable);
+				}
+			}
+			parentScope = tableScope;
+		}
+
+		SqlCall call;
+		SqlNode operand;
+		SqlNode newOperand;
+
+		switch (kind) {
+			case AS:
+				call = (SqlCall) node;
+				if (alias == null) {
+					alias = call.operand(1).toString();
+				}
+				final boolean needAlias = call.operandCount() > 2;
+				expr = call.operand(0);
+				newExpr =
+					registerFrom(
+						parentScope,
+						usingScope,
+						!needAlias,
+						expr,
+						enclosingNode,
+						alias,
+						extendList,
+						forceNullable,
+						lateral);
+				if (newExpr != expr) {
+					call.setOperand(0, newExpr);
+				}
+
+				// If alias has a column list, introduce a namespace to translate
+				// column names. We skipped registering it just now.
+				if (needAlias) {
+					registerNamespace(
+						usingScope,
+						alias,
+						new AliasNamespace(this, call, enclosingNode),
+						forceNullable);
+				}
+				return node;
+			case MATCH_RECOGNIZE:
+				registerMatchRecognize(parentScope, usingScope,
+					(SqlMatchRecognize) node, enclosingNode, alias, forceNullable);
+				return node;
+			case TABLESAMPLE:
+				call = (SqlCall) node;
+				expr = call.operand(0);
+				newExpr =
+					registerFrom(
+						parentScope,
+						usingScope,
+						true,
+						expr,
+						enclosingNode,
+						alias,
+						extendList,
+						forceNullable,
+						lateral);
+				if (newExpr != expr) {
+					call.setOperand(0, newExpr);
+				}
+				return node;
+
+			case JOIN:
+				final SqlJoin join = (SqlJoin) node;
+				final JoinScope joinScope =
+					new JoinScope(parentScope, usingScope, join);
+				scopes.put(join, joinScope);
+				final SqlNode left = join.getLeft();
+				final SqlNode right = join.getRight();
+				final boolean rightIsLateral = isLateral(right);
+				boolean forceLeftNullable = forceNullable;
+				boolean forceRightNullable = forceNullable;
+				switch (join.getJoinType()) {
+					case LEFT:
+						forceRightNullable = true;
+						break;
+					case RIGHT:
+						forceLeftNullable = true;
+						break;
+					case FULL:
+						forceLeftNullable = true;
+						forceRightNullable = true;
+						break;
+				}
+				final SqlNode newLeft =
+					registerFrom(
+						parentScope,
+						joinScope,
+						true,
+						left,
+						left,
+						null,
+						null,
+						forceLeftNullable,
+						lateral);
+				if (newLeft != left) {
+					join.setLeft(newLeft);
+				}
+				final SqlNode newRight =
+					registerFrom(
+						parentScope,
+						joinScope,
+						true,
+						right,
+						right,
+						null,
+						null,
+						forceRightNullable,
+						lateral);
+				if (newRight != right) {
+					join.setRight(newRight);
+				}
+				registerSubQueries(joinScope, join.getCondition());
+				final JoinNamespace joinNamespace = new JoinNamespace(this, join);
+				registerNamespace(null, null, joinNamespace, forceNullable);
+				return join;
+
+			case IDENTIFIER:
+				final SqlIdentifier id = (SqlIdentifier) node;
+				final IdentifierNamespace newNs =
+					new IdentifierNamespace(
+						this, id, extendList, enclosingNode,
+						parentScope);
+				registerNamespace(register ? usingScope : null, alias, newNs,
+					forceNullable);
+				if (tableScope == null) {
+					tableScope = new TableScope(parentScope, node);
+				}
+				tableScope.addChild(newNs, alias, forceNullable);
+				if (extendList != null && extendList.size() != 0) {
+					return enclosingNode;
+				}
+				return newNode;
+
+			case LATERAL:
+				return registerFrom(
+					parentScope,
+					usingScope,
+					register,
+					((SqlCall) node).operand(0),
+					enclosingNode,
+					alias,
+					extendList,
+					forceNullable,
+					true);
+
+			case COLLECTION_TABLE:
+				call = (SqlCall) node;
+				operand = call.operand(0);
+				newOperand =
+					registerFrom(
+						parentScope,
+						usingScope,
+						register,
+						operand,
+						enclosingNode,
+						alias,
+						extendList,
+						forceNullable, lateral);
+				if (newOperand != operand) {
+					call.setOperand(0, newOperand);
+				}
+				scopes.put(node, parentScope);
+				return newNode;
+
+			case UNNEST:
+				if (!lateral) {
+					return registerFrom(parentScope, usingScope, register, node,
+						enclosingNode, alias, extendList, forceNullable, true);
+				}
+				// fall through
+			case SELECT:
+			case UNION:
+			case INTERSECT:
+			case EXCEPT:
+			case VALUES:
+			case WITH:
+			case OTHER_FUNCTION:
+				if (alias == null) {
+					alias = deriveAlias(node, nextGeneratedId++);
+				}
+				registerQuery(
+					parentScope,
+					register ? usingScope : null,
+					node,
+					enclosingNode,
+					alias,
+					forceNullable);
+				return newNode;
+
+			case OVER:
+				if (!shouldAllowOverRelation()) {
+					throw Util.unexpected(kind);
+				}
+				call = (SqlCall) node;
+				final OverScope overScope = new OverScope(usingScope, call);
+				scopes.put(call, overScope);
+				operand = call.operand(0);
+				newOperand =
+					registerFrom(
+						parentScope,
+						overScope,
+						true,
+						operand,
+						enclosingNode,
+						alias,
+						extendList,
+						forceNullable,
+						lateral);
+				if (newOperand != operand) {
+					call.setOperand(0, newOperand);
+				}
+
+				for (ScopeChild child : overScope.children) {
+					registerNamespace(register ? usingScope : null, child.name,
+						child.namespace, forceNullable);
+				}
+
+				return newNode;
+
+			case EXTEND:
+				final SqlCall extend = (SqlCall) node;
+				return registerFrom(parentScope,
+					usingScope,
+					true,
+					extend.getOperandList().get(0),
+					extend,
+					alias,
+					(SqlNodeList) extend.getOperandList().get(1),
+					forceNullable,
+					lateral);
+
+			default:
+				throw Util.unexpected(kind);
+		}
+	}
+
+	private static boolean isLateral(SqlNode node) {
+		switch (node.getKind()) {
+			case LATERAL:
+			case UNNEST:
+				// Per SQL std, UNNEST is implicitly LATERAL.
+				return true;
+			case AS:
+				return isLateral(((SqlCall) node).operand(0));
+			default:
+				return false;
+		}
+	}
+
+	protected boolean shouldAllowOverRelation() {
+		return false;
+	}
+
+	/**
+	 * Creates a namespace for a <code>SELECT</code> node. Derived class may
+	 * override this factory method.
+	 *
+	 * @param select        Select node
+	 * @param enclosingNode Enclosing node
+	 * @return Select namespace
+	 */
+	protected SelectNamespace createSelectNamespace(
+		SqlSelect select,
+		SqlNode enclosingNode) {
+		return new SelectNamespace(this, select, enclosingNode);
+	}
+
+	/**
+	 * Creates a namespace for a set operation (<code>UNION</code>, <code>
+	 * INTERSECT</code>, or <code>EXCEPT</code>). Derived class may override
+	 * this factory method.
+	 *
+	 * @param call          Call to set operation
+	 * @param enclosingNode Enclosing node
+	 * @return Set operation namespace
+	 */
+	protected SetopNamespace createSetopNamespace(
+		SqlCall call,
+		SqlNode enclosingNode) {
+		return new SetopNamespace(this, call, enclosingNode);
+	}
+
+	/**
+	 * Registers a query in a parent scope.
+	 *
+	 * @param parentScope Parent scope which this scope turns to in order to
+	 *                    resolve objects
+	 * @param usingScope  Scope whose child list this scope should add itself to
+	 * @param node        Query node
+	 * @param alias       Name of this query within its parent. Must be specified
+	 *                    if usingScope != null
+	 */
+	private void registerQuery(
+		SqlValidatorScope parentScope,
+		SqlValidatorScope usingScope,
+		SqlNode node,
+		SqlNode enclosingNode,
+		String alias,
+		boolean forceNullable) {
+		Preconditions.checkArgument(usingScope == null || alias != null);
+		registerQuery(
+			parentScope,
+			usingScope,
+			node,
+			enclosingNode,
+			alias,
+			forceNullable,
+			true);
+	}
+
+	/**
+	 * Registers a query in a parent scope.
+	 *
+	 * @param parentScope Parent scope which this scope turns to in order to
+	 *                    resolve objects
+	 * @param usingScope  Scope whose child list this scope should add itself to
+	 * @param node        Query node
+	 * @param alias       Name of this query within its parent. Must be specified
+	 *                    if usingScope != null
+	 * @param checkUpdate if true, validate that the update feature is supported
+	 *                    if validating the update statement
+	 */
+	private void registerQuery(
+		SqlValidatorScope parentScope,
+		SqlValidatorScope usingScope,
+		SqlNode node,
+		SqlNode enclosingNode,
+		String alias,
+		boolean forceNullable,
+		boolean checkUpdate) {
+		Objects.requireNonNull(node);
+		Objects.requireNonNull(enclosingNode);
+		Preconditions.checkArgument(usingScope == null || alias != null);
+
+		SqlCall call;
+		List<SqlNode> operands;
+		switch (node.getKind()) {
+			case SELECT:
+				final SqlSelect select = (SqlSelect) node;
+				final SelectNamespace selectNs =
+					createSelectNamespace(select, enclosingNode);
+				registerNamespace(usingScope, alias, selectNs, forceNullable);
+				final SqlValidatorScope windowParentScope =
+					(usingScope != null) ? usingScope : parentScope;
+				SelectScope selectScope =
+					new SelectScope(parentScope, windowParentScope, select);
+				scopes.put(select, selectScope);
+
+				// Start by registering the WHERE clause
+				whereScopes.put(select, selectScope);
+				registerOperandSubQueries(
+					selectScope,
+					select,
+					SqlSelect.WHERE_OPERAND);
+
+				// Register FROM with the inherited scope 'parentScope', not
+				// 'selectScope', otherwise tables in the FROM clause would be
+				// able to see each other.
+				final SqlNode from = select.getFrom();
+				if (from != null) {
+					final SqlNode newFrom =
+						registerFrom(
+							parentScope,
+							selectScope,
+							true,
+							from,
+							from,
+							null,
+							null,
+							false,
+							false);
+					if (newFrom != from) {
+						select.setFrom(newFrom);
+					}
+				}
+
+				// If this is an aggregating query, the SELECT list and HAVING
+				// clause use a different scope, where you can only reference
+				// columns which are in the GROUP BY clause.
+				SqlValidatorScope aggScope = selectScope;
+				if (isAggregate(select)) {
+					aggScope =
+						new AggregatingSelectScope(selectScope, select, false);
+					selectScopes.put(select, aggScope);
+				} else {
+					selectScopes.put(select, selectScope);
+				}
+				if (select.getGroup() != null) {
+					GroupByScope groupByScope =
+						new GroupByScope(selectScope, select.getGroup(), select);
+					groupByScopes.put(select, groupByScope);
+					registerSubQueries(groupByScope, select.getGroup());
+				}
+				registerOperandSubQueries(
+					aggScope,
+					select,
+					SqlSelect.HAVING_OPERAND);
+				registerSubQueries(aggScope, select.getSelectList());
+				final SqlNodeList orderList = select.getOrderList();
+				if (orderList != null) {
+					// If the query is 'SELECT DISTINCT', restrict the columns
+					// available to the ORDER BY clause.
+					if (select.isDistinct()) {
+						aggScope =
+							new AggregatingSelectScope(selectScope, select, true);
+					}
+					OrderByScope orderScope =
+						new OrderByScope(aggScope, orderList, select);
+					orderScopes.put(select, orderScope);
+					registerSubQueries(orderScope, orderList);
+
+					if (!isAggregate(select)) {
+						// Since this is not an aggregating query,
+						// there cannot be any aggregates in the ORDER BY clause.
+						SqlNode agg = aggFinder.findAgg(orderList);
+						if (agg != null) {
+							throw newValidationError(agg, RESOURCE.aggregateIllegalInOrderBy());
+						}
+					}
+				}
+				break;
+
+			case INTERSECT:
+				validateFeature(RESOURCE.sQLFeature_F302(), node.getParserPosition());
+				registerSetop(
+					parentScope,
+					usingScope,
+					node,
+					node,
+					alias,
+					forceNullable);
+				break;
+
+			case EXCEPT:
+				validateFeature(RESOURCE.sQLFeature_E071_03(), node.getParserPosition());
+				registerSetop(
+					parentScope,
+					usingScope,
+					node,
+					node,
+					alias,
+					forceNullable);
+				break;
+
+			case UNION:
+				registerSetop(
+					parentScope,
+					usingScope,
+					node,
+					node,
+					alias,
+					forceNullable);
+				break;
+
+			case WITH:
+				registerWith(parentScope, usingScope, (SqlWith) node, enclosingNode,
+					alias, forceNullable, checkUpdate);
+				break;
+
+			case VALUES:
+				call = (SqlCall) node;
+				scopes.put(call, parentScope);
+				final TableConstructorNamespace tableConstructorNamespace =
+					new TableConstructorNamespace(
+						this,
+						call,
+						parentScope,
+						enclosingNode);
+				registerNamespace(
+					usingScope,
+					alias,
+					tableConstructorNamespace,
+					forceNullable);
+				operands = call.getOperandList();
+				for (int i = 0; i < operands.size(); ++i) {
+					assert operands.get(i).getKind() == SqlKind.ROW;
+
+					// FIXME jvs 9-Feb-2005:  Correlation should
+					// be illegal in these sub-queries.  Same goes for
+					// any non-lateral SELECT in the FROM list.
+					registerOperandSubQueries(parentScope, call, i);
+				}
+				break;
+
+			case INSERT:
+				SqlInsert insertCall = (SqlInsert) node;
+				InsertNamespace insertNs =
+					new InsertNamespace(
+						this,
+						insertCall,
+						enclosingNode,
+						parentScope);
+				registerNamespace(usingScope, null, insertNs, forceNullable);
+				registerQuery(
+					parentScope,
+					usingScope,
+					insertCall.getSource(),
+					enclosingNode,
+					null,
+					false);
+				break;
+
+			case DELETE:
+				SqlDelete deleteCall = (SqlDelete) node;
+				DeleteNamespace deleteNs =
+					new DeleteNamespace(
+						this,
+						deleteCall,
+						enclosingNode,
+						parentScope);
+				registerNamespace(usingScope, null, deleteNs, forceNullable);
+				registerQuery(
+					parentScope,
+					usingScope,
+					deleteCall.getSourceSelect(),
+					enclosingNode,
+					null,
+					false);
+				break;
+
+			case UPDATE:
+				if (checkUpdate) {
+					validateFeature(RESOURCE.sQLFeature_E101_03(),
+						node.getParserPosition());
+				}
+				SqlUpdate updateCall = (SqlUpdate) node;
+				UpdateNamespace updateNs =
+					new UpdateNamespace(
+						this,
+						updateCall,
+						enclosingNode,
+						parentScope);
+				registerNamespace(usingScope, null, updateNs, forceNullable);
+				registerQuery(
+					parentScope,
+					usingScope,
+					updateCall.getSourceSelect(),
+					enclosingNode,
+					null,
+					false);
+				break;
+
+			case MERGE:
+				validateFeature(RESOURCE.sQLFeature_F312(), node.getParserPosition());
+				SqlMerge mergeCall = (SqlMerge) node;
+				MergeNamespace mergeNs =
+					new MergeNamespace(
+						this,
+						mergeCall,
+						enclosingNode,
+						parentScope);
+				registerNamespace(usingScope, null, mergeNs, forceNullable);
+				registerQuery(
+					parentScope,
+					usingScope,
+					mergeCall.getSourceSelect(),
+					enclosingNode,
+					null,
+					false);
+
+				// update call can reference either the source table reference
+				// or the target table, so set its parent scope to the merge's
+				// source select; when validating the update, skip the feature
+				// validation check
+				if (mergeCall.getUpdateCall() != null) {
+					registerQuery(
+						whereScopes.get(mergeCall.getSourceSelect()),
+						null,
+						mergeCall.getUpdateCall(),
+						enclosingNode,
+						null,
+						false,
+						false);
+				}
+				if (mergeCall.getInsertCall() != null) {
+					registerQuery(
+						parentScope,
+						null,
+						mergeCall.getInsertCall(),
+						enclosingNode,
+						null,
+						false);
+				}
+				break;
+
+			case UNNEST:
+				call = (SqlCall) node;
+				final UnnestNamespace unnestNs =
+					new UnnestNamespace(this, call, parentScope, enclosingNode);
+				registerNamespace(
+					usingScope,
+					alias,
+					unnestNs,
+					forceNullable);
+				registerOperandSubQueries(parentScope, call, 0);
+				scopes.put(node, parentScope);
+				break;
+
+			case OTHER_FUNCTION:
+				call = (SqlCall) node;
+				ProcedureNamespace procNs =
+					new ProcedureNamespace(
+						this,
+						parentScope,
+						call,
+						enclosingNode);
+				registerNamespace(
+					usingScope,
+					alias,
+					procNs,
+					forceNullable);
+				registerSubQueries(parentScope, call);
+				break;
+
+			case MULTISET_QUERY_CONSTRUCTOR:
+			case MULTISET_VALUE_CONSTRUCTOR:
+				validateFeature(RESOURCE.sQLFeature_S271(), node.getParserPosition());
+				call = (SqlCall) node;
+				CollectScope cs = new CollectScope(parentScope, usingScope, call);
+				final CollectNamespace tableConstructorNs =
+					new CollectNamespace(call, cs, enclosingNode);
+				final String alias2 = deriveAlias(node, nextGeneratedId++);
+				registerNamespace(
+					usingScope,
+					alias2,
+					tableConstructorNs,
+					forceNullable);
+				operands = call.getOperandList();
+				for (int i = 0; i < operands.size(); i++) {
+					registerOperandSubQueries(parentScope, call, i);
+				}
+				break;
+
+			default:
+				throw Util.unexpected(node.getKind());
+		}
+	}
+
+	private void registerSetop(
+		SqlValidatorScope parentScope,
+		SqlValidatorScope usingScope,
+		SqlNode node,
+		SqlNode enclosingNode,
+		String alias,
+		boolean forceNullable) {
+		SqlCall call = (SqlCall) node;
+		final SetopNamespace setopNamespace =
+			createSetopNamespace(call, enclosingNode);
+		registerNamespace(usingScope, alias, setopNamespace, forceNullable);
+
+		// A setop is in the same scope as its parent.
+		scopes.put(call, parentScope);
+		for (SqlNode operand : call.getOperandList()) {
+			registerQuery(
+				parentScope,
+				null,
+				operand,
+				operand,
+				null,
+				false);
+		}
+	}
+
+	private void registerWith(
+		SqlValidatorScope parentScope,
+		SqlValidatorScope usingScope,
+		SqlWith with,
+		SqlNode enclosingNode,
+		String alias,
+		boolean forceNullable,
+		boolean checkUpdate) {
+		final WithNamespace withNamespace =
+			new WithNamespace(this, with, enclosingNode);
+		registerNamespace(usingScope, alias, withNamespace, forceNullable);
+
+		SqlValidatorScope scope = parentScope;
+		for (SqlNode withItem_ : with.withList) {
+			final SqlWithItem withItem = (SqlWithItem) withItem_;
+			final WithScope withScope = new WithScope(scope, withItem);
+			scopes.put(withItem, withScope);
+
+			registerQuery(scope, null, withItem.query, with,
+				withItem.name.getSimple(), false);
+			registerNamespace(null, alias,
+				new WithItemNamespace(this, withItem, enclosingNode),
+				false);
+			scope = withScope;
+		}
+
+		registerQuery(scope, null, with.body, enclosingNode, alias, forceNullable,
+			checkUpdate);
+	}
+
+	public boolean isAggregate(SqlSelect select) {
+		if (getAggregate(select) != null) {
+			return true;
+		}
+		// Also when nested window aggregates are present
+		for (SqlCall call : overFinder.findAll(select.getSelectList())) {
+			assert call.getKind() == SqlKind.OVER;
+			if (isNestedAggregateWindow(call.operand(0))) {
+				return true;
+			}
+			if (isOverAggregateWindow(call.operand(1))) {
+				return true;
+			}
+		}
+		return false;
+	}
+
+	protected boolean isNestedAggregateWindow(SqlNode node) {
+		AggFinder nestedAggFinder =
+			new AggFinder(opTab, false, false, false, aggFinder);
+		return nestedAggFinder.findAgg(node) != null;
+	}
+
+	protected boolean isOverAggregateWindow(SqlNode node) {
+		return aggFinder.findAgg(node) != null;
+	}
+
+	/** Returns the parse tree node (GROUP BY, HAVING, or an aggregate function
+	 * call) that causes {@code select} to be an aggregate query, or null if it
+	 * is not an aggregate query.
+	 *
+	 * <p>The node is useful context for error messages,
+	 * but you cannot assume that the node is the only aggregate function. */
+	protected SqlNode getAggregate(SqlSelect select) {
+		SqlNode node = select.getGroup();
+		if (node != null) {
+			return node;
+		}
+		node = select.getHaving();
+		if (node != null) {
+			return node;
+		}
+		return getAgg(select);
+	}
+
+	/** If there is at least one call to an aggregate function, returns the
+	 * first. */
+	private SqlNode getAgg(SqlSelect select) {
+		final SelectScope selectScope = getRawSelectScope(select);
+		if (selectScope != null) {
+			final List<SqlNode> selectList = selectScope.getExpandedSelectList();
+			if (selectList != null) {
+				return aggFinder.findAgg(selectList);
+			}
+		}
+		return aggFinder.findAgg(select.getSelectList());
+	}
+
+	@SuppressWarnings("deprecation")
+	public boolean isAggregate(SqlNode selectNode) {
+		return aggFinder.findAgg(selectNode) != null;
+	}
+
+	private void validateNodeFeature(SqlNode node) {
+		switch (node.getKind()) {
+			case MULTISET_VALUE_CONSTRUCTOR:
+				validateFeature(RESOURCE.sQLFeature_S271(), node.getParserPosition());
+				break;
+		}
+	}
+
+	private void registerSubQueries(
+		SqlValidatorScope parentScope,
+		SqlNode node) {
+		if (node == null) {
+			return;
+		}
+		if (node.getKind().belongsTo(SqlKind.QUERY)
+			|| node.getKind() == SqlKind.MULTISET_QUERY_CONSTRUCTOR
+			|| node.getKind() == SqlKind.MULTISET_VALUE_CONSTRUCTOR) {
+			registerQuery(parentScope, null, node, node, null, false);
+		} else if (node instanceof SqlCall) {
+			validateNodeFeature(node);
+			SqlCall call = (SqlCall) node;
+			for (int i = 0; i < call.operandCount(); i++) {
+				registerOperandSubQueries(parentScope, call, i);
+			}
+		} else if (node instanceof SqlNodeList) {
+			SqlNodeList list = (SqlNodeList) node;
+			for (int i = 0, count = list.size(); i < count; i++) {
+				SqlNode listNode = list.get(i);
+				if (listNode.getKind().belongsTo(SqlKind.QUERY)) {
+					listNode =
+						SqlStdOperatorTable.SCALAR_QUERY.createCall(
+							listNode.getParserPosition(),
+							listNode);
+					list.set(i, listNode);
+				}
+				registerSubQueries(parentScope, listNode);
+			}
+		} else {
+			// atomic node -- can be ignored
+		}
+	}
+
+	/**
+	 * Registers any sub-queries inside a given call operand, and converts the
+	 * operand to a scalar sub-query if the operator requires it.
+	 *
+	 * @param parentScope    Parent scope
+	 * @param call           Call
+	 * @param operandOrdinal Ordinal of operand within call
+	 * @see SqlOperator#argumentMustBeScalar(int)
+	 */
+	private void registerOperandSubQueries(
+		SqlValidatorScope parentScope,
+		SqlCall call,
+		int operandOrdinal) {
+		SqlNode operand = call.operand(operandOrdinal);
+		if (operand == null) {
+			return;
+		}
+		if (operand.getKind().belongsTo(SqlKind.QUERY)
+			&& call.getOperator().argumentMustBeScalar(operandOrdinal)) {
+			operand =
+				SqlStdOperatorTable.SCALAR_QUERY.createCall(
+					operand.getParserPosition(),
+					operand);
+			call.setOperand(operandOrdinal, operand);
+		}
+		registerSubQueries(parentScope, operand);
+	}
+
+	public void validateIdentifier(SqlIdentifier id, SqlValidatorScope scope) {
+		final SqlQualified fqId = scope.fullyQualify(id);
+		if (expandColumnReferences) {
+			// NOTE jvs 9-Apr-2007: this doesn't cover ORDER BY, which has its
+			// own ideas about qualification.
+			id.assignNamesFrom(fqId.identifier);
+		} else {
+			Util.discard(fqId);
+		}
+	}
+
+	public void validateLiteral(SqlLiteral literal) {
+		switch (literal.getTypeName()) {
+			case DECIMAL:
+				// Decimal and long have the same precision (as 64-bit integers), so
+				// the unscaled value of a decimal must fit into a long.
+
+				// REVIEW jvs 4-Aug-2004:  This should probably be calling over to
+				// the available calculator implementations to see what they
+				// support.  For now use ESP instead.
+				//
+				// jhyde 2006/12/21: I think the limits should be baked into the
+				// type system, not dependent on the calculator implementation.
+				BigDecimal bd = (BigDecimal) literal.getValue();
+				BigInteger unscaled = bd.unscaledValue();
+				long longValue = unscaled.longValue();
+				if (!BigInteger.valueOf(longValue).equals(unscaled)) {
+					// overflow
+					throw newValidationError(literal,
+						RESOURCE.numberLiteralOutOfRange(bd.toString()));
+				}
+				break;
+
+			case DOUBLE:
+				validateLiteralAsDouble(literal);
+				break;
+
+			case BINARY:
+				final BitString bitString = (BitString) literal.getValue();
+				if ((bitString.getBitCount() % 8) != 0) {
+					throw newValidationError(literal, RESOURCE.binaryLiteralOdd());
+				}
+				break;
+
+			case DATE:
+			case TIME:
+			case TIMESTAMP:
+				Calendar calendar = literal.getValueAs(Calendar.class);
+				final int year = calendar.get(Calendar.YEAR);
+				final int era = calendar.get(Calendar.ERA);
+				if (year < 1 || era == GregorianCalendar.BC || year > 9999) {
+					throw newValidationError(literal,
+						RESOURCE.dateLiteralOutOfRange(literal.toString()));
+				}
+				break;
+
+			case INTERVAL_YEAR:
+			case INTERVAL_YEAR_MONTH:
+			case INTERVAL_MONTH:
+			case INTERVAL_DAY:
+			case INTERVAL_DAY_HOUR:
+			case INTERVAL_DAY_MINUTE:
+			case INTERVAL_DAY_SECOND:
+			case INTERVAL_HOUR:
+			case INTERVAL_HOUR_MINUTE:
+			case INTERVAL_HOUR_SECOND:
+			case INTERVAL_MINUTE:
+			case INTERVAL_MINUTE_SECOND:
+			case INTERVAL_SECOND:
+				if (literal instanceof SqlIntervalLiteral) {
+					SqlIntervalLiteral.IntervalValue interval =
+						(SqlIntervalLiteral.IntervalValue)
+							literal.getValue();
+					SqlIntervalQualifier intervalQualifier =
+						interval.getIntervalQualifier();
+
+					// ensure qualifier is good before attempting to validate literal
+					validateIntervalQualifier(intervalQualifier);
+					String intervalStr = interval.getIntervalLiteral();
+					// throws CalciteContextException if string is invalid
+					int[] values = intervalQualifier.evaluateIntervalLiteral(intervalStr,
+						literal.getParserPosition(), typeFactory.getTypeSystem());
+					Util.discard(values);
+				}
+				break;
+			default:
+				// default is to do nothing
+		}
+	}
+
+	private void validateLiteralAsDouble(SqlLiteral literal) {
+		BigDecimal bd = (BigDecimal) literal.getValue();
+		double d = bd.doubleValue();
+		if (Double.isInfinite(d) || Double.isNaN(d)) {
+			// overflow
+			throw newValidationError(literal,
+				RESOURCE.numberLiteralOutOfRange(Util.toScientificNotation(bd)));
+		}
+
+		// REVIEW jvs 4-Aug-2004:  what about underflow?
+	}
+
+	public void validateIntervalQualifier(SqlIntervalQualifier qualifier) {
+		assert qualifier != null;
+		boolean startPrecisionOutOfRange = false;
+		boolean fractionalSecondPrecisionOutOfRange = false;
+		final RelDataTypeSystem typeSystem = typeFactory.getTypeSystem();
+
+		final int startPrecision = qualifier.getStartPrecision(typeSystem);
+		final int fracPrecision =
+			qualifier.getFractionalSecondPrecision(typeSystem);
+		final int maxPrecision = typeSystem.getMaxPrecision(qualifier.typeName());
+		final int minPrecision = qualifier.typeName().getMinPrecision();
+		final int minScale = qualifier.typeName().getMinScale();
+		final int maxScale = typeSystem.getMaxScale(qualifier.typeName());
+		if (qualifier.isYearMonth()) {
+			if (startPrecision < minPrecision || startPrecision > maxPrecision) {
+				startPrecisionOutOfRange = true;
+			} else {
+				if (fracPrecision < minScale || fracPrecision > maxScale) {
+					fractionalSecondPrecisionOutOfRange = true;
+				}
+			}
+		} else {
+			if (startPrecision < minPrecision || startPrecision > maxPrecision) {
+				startPrecisionOutOfRange = true;
+			} else {
+				if (fracPrecision < minScale || fracPrecision > maxScale) {
+					fractionalSecondPrecisionOutOfRange = true;
+				}
+			}
+		}
+
+		if (startPrecisionOutOfRange) {
+			throw newValidationError(qualifier,
+				RESOURCE.intervalStartPrecisionOutOfRange(startPrecision,
+					"INTERVAL " + qualifier));
+		} else if (fractionalSecondPrecisionOutOfRange) {
+			throw newValidationError(qualifier,
+				RESOURCE.intervalFractionalSecondPrecisionOutOfRange(
+					fracPrecision,
+					"INTERVAL " + qualifier));
+		}
+	}
+
+	/**
+	 * Validates the FROM clause of a query, or (recursively) a child node of
+	 * the FROM clause: AS, OVER, JOIN, VALUES, or sub-query.
+	 *
+	 * @param node          Node in FROM clause, typically a table or derived
+	 *                      table
+	 * @param targetRowType Desired row type of this expression, or
+	 *                      {@link #unknownType} if not fussy. Must not be null.
+	 * @param scope         Scope
+	 */
+	protected void validateFrom(
+		SqlNode node,
+		RelDataType targetRowType,
+		SqlValidatorScope scope) {
+		Objects.requireNonNull(targetRowType);
+		switch (node.getKind()) {
+			case AS:
+				validateFrom(
+					((SqlCall) node).operand(0),
+					targetRowType,
+					scope);
+				break;
+			case VALUES:
+				validateValues((SqlCall) node, targetRowType, scope);
+				break;
+			case JOIN:
+				validateJoin((SqlJoin) node, scope);
+				break;
+			case OVER:
+				validateOver((SqlCall) node, scope);
+				break;
+			default:
+				validateQuery(node, scope, targetRowType);
+				break;
+		}
+
+		// Validate the namespace representation of the node, just in case the
+		// validation did not occur implicitly.
+		getNamespace(node, scope).validate(targetRowType);
+	}
+
+	protected void validateOver(SqlCall call, SqlValidatorScope scope) {
+		throw new AssertionError("OVER unexpected in this context");
+	}
+
+	private void checkRollUpInUsing(SqlIdentifier identifier, SqlNode leftOrRight) {
+		leftOrRight = stripAs(leftOrRight);
+		// if it's not a SqlIdentifier then that's fine, it'll be validated somewhere else.
+		if (leftOrRight instanceof SqlIdentifier) {
+			SqlIdentifier from = (SqlIdentifier) leftOrRight;
+			Table table = findTable(catalogReader.getRootSchema(), Util.last(from.names),
+				catalogReader.nameMatcher().isCaseSensitive());
+			String name = Util.last(identifier.names);
+
+			if (table != null && table.isRolledUp(name)) {
+				throw newValidationError(identifier, RESOURCE.rolledUpNotAllowed(name, "USING"));
+			}
+		}
+	}
+
+	protected void validateJoin(SqlJoin join, SqlValidatorScope scope) {
+		SqlNode left = join.getLeft();
+		SqlNode right = join.getRight();
+		SqlNode condition = join.getCondition();
+		boolean natural = join.isNatural();
+		final JoinType joinType = join.getJoinType();
+		final JoinConditionType conditionType = join.getConditionType();
+		final SqlValidatorScope joinScope = scopes.get(join);
+		validateFrom(left, unknownType, joinScope);
+		validateFrom(right, unknownType, joinScope);
+
+		// Validate condition.
+		switch (conditionType) {
+			case NONE:
+				Preconditions.checkArgument(condition == null);
+				break;
+			case ON:
+				Preconditions.checkArgument(condition != null);
+				SqlNode expandedCondition = expand(condition, joinScope);
+				join.setOperand(5, expandedCondition);
+				condition = join.getCondition();
+				validateWhereOrOn(joinScope, condition, "ON");
+				checkRollUp(null, join, condition, joinScope, "ON");
+				break;
+			case USING:
+				SqlNodeList list = (SqlNodeList) condition;
+
+				// Parser ensures that using clause is not empty.
+				Preconditions.checkArgument(list.size() > 0, "Empty USING clause");
+				for (SqlNode node : list) {
+					SqlIdentifier id = (SqlIdentifier) node;
+					final RelDataType leftColType = validateUsingCol(id, left);
+					final RelDataType rightColType = validateUsingCol(id, right);
+					if (!SqlTypeUtil.isComparable(leftColType, rightColType)) {
+						throw newValidationError(id,
+							RESOURCE.naturalOrUsingColumnNotCompatible(id.getSimple(),
+								leftColType.toString(), rightColType.toString()));
+					}
+					checkRollUpInUsing(id, left);
+					checkRollUpInUsing(id, right);
+				}
+				break;
+			default:
+				throw Util.unexpected(conditionType);
+		}
+
+		// Validate NATURAL.
+		if (natural) {
+			if (condition != null) {
+				throw newValidationError(condition,
+					RESOURCE.naturalDisallowsOnOrUsing());
+			}
+
+			// Join on fields that occur exactly once on each side. Ignore
+			// fields that occur more than once on either side.
+			final RelDataType leftRowType = getNamespace(left).getRowType();
+			final RelDataType rightRowType = getNamespace(right).getRowType();
+			final SqlNameMatcher nameMatcher = catalogReader.nameMatcher();
+			List<String> naturalColumnNames =
+				SqlValidatorUtil.deriveNaturalJoinColumnList(nameMatcher,
+					leftRowType, rightRowType);
+
+			// Check compatibility of the chosen columns.
+			for (String name : naturalColumnNames) {
+				final RelDataType leftColType =
+					nameMatcher.field(leftRowType, name).getType();
+				final RelDataType rightColType =
+					nameMatcher.field(rightRowType, name).getType();
+				if (!SqlTypeUtil.isComparable(leftColType, rightColType)) {
+					throw newValidationError(join,
+						RESOURCE.naturalOrUsingColumnNotCompatible(name,
+							leftColType.toString(), rightColType.toString()));
+				}
+			}
+		}
+
+		// Which join types require/allow a ON/USING condition, or allow
+		// a NATURAL keyword?
+		switch (joinType) {
+			case LEFT_SEMI_JOIN:
+				if (!conformance.isLiberal()) {
+					throw newValidationError(join.getJoinTypeNode(),
+						RESOURCE.dialectDoesNotSupportFeature("LEFT SEMI JOIN"));
+				}
+				// fall through
+			case INNER:
+			case LEFT:
+			case RIGHT:
+			case FULL:
+				if ((condition == null) && !natural) {
+					throw newValidationError(join, RESOURCE.joinRequiresCondition());
+				}
+				break;
+			case COMMA:
+			case CROSS:
+				if (condition != null) {
+					throw newValidationError(join.getConditionTypeNode(),
+						RESOURCE.crossJoinDisallowsCondition());
+				}
+				if (natural) {
+					throw newValidationError(join.getConditionTypeNode(),
+						RESOURCE.crossJoinDisallowsCondition());
+				}
+				break;
+			default:
+				throw Util.unexpected(joinType);
+		}
+	}
+
+	/**
+	 * Throws an error if there is an aggregate or windowed aggregate in the
+	 * given clause.
+	 *
+	 * @param aggFinder Finder for the particular kind(s) of aggregate function
+	 * @param node      Parse tree
+	 * @param clause    Name of clause: "WHERE", "GROUP BY", "ON"
+	 */
+	private void validateNoAggs(AggFinder aggFinder, SqlNode node,
+		String clause) {
+		final SqlCall agg = aggFinder.findAgg(node);
+		if (agg == null) {
+			return;
+		}
+		final SqlOperator op = agg.getOperator();
+		if (op == SqlStdOperatorTable.OVER) {
+			throw newValidationError(agg,
+				RESOURCE.windowedAggregateIllegalInClause(clause));
+		} else if (op.isGroup() || op.isGroupAuxiliary()) {
+			throw newValidationError(agg,
+				RESOURCE.groupFunctionMustAppearInGroupByClause(op.getName()));
+		} else {
+			throw newValidationError(agg,
+				RESOURCE.aggregateIllegalInClause(clause));
+		}
+	}
+
+	private RelDataType validateUsingCol(SqlIdentifier id, SqlNode leftOrRight) {
+		if (id.names.size() == 1) {
+			String name = id.names.get(0);
+			final SqlValidatorNamespace namespace = getNamespace(leftOrRight);
+			final RelDataType rowType = namespace.getRowType();
+			final SqlNameMatcher nameMatcher = catalogReader.nameMatcher();
+			final RelDataTypeField field = nameMatcher.field(rowType, name);
+			if (field != null) {
+				if (nameMatcher.frequency(rowType.getFieldNames(), name) > 1) {
+					throw newValidationError(id,
+						RESOURCE.columnInUsingNotUnique(id.toString()));
+				}
+				return field.getType();
+			}
+		}
+		throw newValidationError(id, RESOURCE.columnNotFound(id.toString()));
+	}
+
+	/**
+	 * Validates a SELECT statement.
+	 *
+	 * @param select        Select statement
+	 * @param targetRowType Desired row type, must not be null, may be the data
+	 *                      type 'unknown'.
+	 */
+	protected void validateSelect(
+		SqlSelect select,
+		RelDataType targetRowType) {
+		assert targetRowType != null;
+		// Namespace is either a select namespace or a wrapper around one.
+		final SelectNamespace ns =
+			getNamespace(select).unwrap(SelectNamespace.class);
+
+		// Its rowtype is null, meaning it hasn't been validated yet.
+		// This is important, because we need to take the targetRowType into
+		// account.
+		assert ns.rowType == null;
+
+		if (select.isDistinct()) {
+			validateFeature(RESOURCE.sQLFeature_E051_01(),
+				select.getModifierNode(SqlSelectKeyword.DISTINCT)
+					.getParserPosition());
+		}
+
+		final SqlNodeList selectItems = select.getSelectList();
+		RelDataType fromType = unknownType;
+		if (selectItems.size() == 1) {
+			final SqlNode selectItem = selectItems.get(0);
+			if (selectItem instanceof SqlIdentifier) {
+				SqlIdentifier id = (SqlIdentifier) selectItem;
+				if (id.isStar() && (id.names.size() == 1)) {
+					// Special case: for INSERT ... VALUES(?,?), the SQL
+					// standard says we're supposed to propagate the target
+					// types down.  So iff the select list is an unqualified
+					// star (as it will be after an INSERT ... VALUES has been
+					// expanded), then propagate.
+					fromType = targetRowType;
+				}
+			}
+		}
+
+		// Make sure that items in FROM clause have distinct aliases.
+		final SelectScope fromScope = (SelectScope) getFromScope(select);
+		List<String> names = fromScope.getChildNames();
+		if (!catalogReader.nameMatcher().isCaseSensitive()) {
+			names = Lists.transform(names, s -> s.toUpperCase(Locale.ROOT));
+		}
+		final int duplicateAliasOrdinal = Util.firstDuplicate(names);
+		if (duplicateAliasOrdinal >= 0) {
+			final ScopeChild child =
+				fromScope.children.get(duplicateAliasOrdinal);
+			throw newValidationError(child.namespace.getEnclosingNode(),
+				RESOURCE.fromAliasDuplicate(child.name));
+		}
+
+		if (select.getFrom() == null) {
+			if (conformance.isFromRequired()) {
+				throw newValidationError(select, RESOURCE.selectMissingFrom());
+			}
+		} else {
+			validateFrom(select.getFrom(), fromType, fromScope);
+		}
+
+		validateWhereClause(select);
+		validateGroupClause(select);
+		validateHavingClause(select);
+		validateWindowClause(select);
+		handleOffsetFetch(select.getOffset(), select.getFetch());
+
+		// Validate the SELECT clause late, because a select item might
+		// depend on the GROUP BY list, or the window function might reference
+		// window name in the WINDOW clause etc.
+		final RelDataType rowType =
+			validateSelectList(selectItems, select, targetRowType);
+		ns.setType(rowType);
+
+		// Validate ORDER BY after we have set ns.rowType because in some
+		// dialects you can refer to columns of the select list, e.g.
+		// "SELECT empno AS x FROM emp ORDER BY x"
+		validateOrderList(select);
+
+		if (shouldCheckForRollUp(select.getFrom())) {
+			checkRollUpInSelectList(select);
+			checkRollUp(null, select, select.getWhere(), getWhereScope(select));
+			checkRollUp(null, select, select.getHaving(), getHavingScope(select));
+			checkRollUpInWindowDecl(select);
+			checkRollUpInGroupBy(select);
+			checkRollUpInOrderBy(select);
+		}
+	}
+
+	private void checkRollUpInSelectList(SqlSelect select) {
+		SqlValidatorScope scope = getSelectScope(select);
+		for (SqlNode item : select.getSelectList()) {
+			checkRollUp(null, select, item, scope);
+		}
+	}
+
+	private void checkRollUpInGroupBy(SqlSelect select) {
+		SqlNodeList group = select.getGroup();
+		if (group != null) {
+			for (SqlNode node : group) {
+				checkRollUp(null, select, node, getGroupScope(select), "GROUP BY");
+			}
+		}
+	}
+
+	private void checkRollUpInOrderBy(SqlSelect select) {
+		SqlNodeList orderList = select.getOrderList();
+		if (orderList != null) {
+			for (SqlNode node : orderList) {
+				checkRollUp(null, select, node, getOrderScope(select), "ORDER BY");
+			}
+		}
+	}
+
+	private void checkRollUpInWindow(SqlWindow window, SqlValidatorScope scope) {
+		if (window != null) {
+			for (SqlNode node : window.getPartitionList()) {
+				checkRollUp(null, window, node, scope, "PARTITION BY");
+			}
+
+			for (SqlNode node : window.getOrderList()) {
+				checkRollUp(null, window, node, scope, "ORDER BY");
+			}
+		}
+	}
+
+	private void checkRollUpInWindowDecl(SqlSelect select) {
+		for (SqlNode decl : select.getWindowList()) {
+			checkRollUpInWindow((SqlWindow) decl, getSelectScope(select));
+		}
+	}
+
+	private SqlNode stripDot(SqlNode node) {
+		if (node != null && node.getKind() == SqlKind.DOT) {
+			return stripDot(((SqlCall) node).operand(0));
+		}
+		return node;
+	}
+
+	private void checkRollUp(SqlNode grandParent, SqlNode parent,
+		SqlNode current, SqlValidatorScope scope, String optionalClause) {
+		current = stripAs(current);
+		if (current instanceof SqlCall && !(current instanceof SqlSelect)) {
+			// Validate OVER separately
+			checkRollUpInWindow(getWindowInOver(current), scope);
+			current = stripOver(current);
+
+			List<SqlNode> children = ((SqlCall) stripDot(current)).getOperandList();
+			for (SqlNode child : children) {
+				checkRollUp(parent, current, child, scope, optionalClause);
+			}
+		} else if (current instanceof SqlIdentifier) {
+			SqlIdentifier id = (SqlIdentifier) current;
+			if (!id.isStar() && isRolledUpColumn(id, scope)) {
+				if (!isAggregation(parent.getKind())
+					|| !isRolledUpColumnAllowedInAgg(id, scope, (SqlCall) parent, grandParent)) {
+					String context = optionalClause != null ? optionalClause : parent.getKind().toString();
+					throw newValidationError(id,
+						RESOURCE.rolledUpNotAllowed(deriveAlias(id, 0), context));
+				}
+			}
+		}
+	}
+
+	private void checkRollUp(SqlNode grandParent, SqlNode parent,
+		SqlNode current, SqlValidatorScope scope) {
+		checkRollUp(grandParent, parent, current, scope, null);
+	}
+
+	private SqlWindow getWindowInOver(SqlNode over) {
+		if (over.getKind() == SqlKind.OVER) {
+			SqlNode window = ((SqlCall) over).getOperandList().get(1);
+			if (window instanceof SqlWindow) {
+				return (SqlWindow) window;
+			}
+			// SqlIdentifier, gets validated elsewhere
+			return null;
+		}
+		return null;
+	}
+
+	private static SqlNode stripOver(SqlNode node) {
+		switch (node.getKind()) {
+			case OVER:
+				return ((SqlCall) node).getOperandList().get(0);
+			default:
+				return node;
+		}
+	}
+
+	private Pair<String, String> findTableColumnPair(SqlIdentifier identifier,
+		SqlValidatorScope scope) {
+		SqlCall call = SqlUtil.makeCall(getOperatorTable(), identifier);
+		if (call != null) {
+			return null;
+		}
+		SqlQualified qualified = scope.fullyQualify(identifier);
+		List<String> names = qualified.identifier.names;
+
+		if (names.size() < 2) {
+			return null;
+		}
+
+		return new Pair<>(names.get(names.size() - 2), Util.last(names));
+	}
+
+	// Returns true iff the given column is valid inside the given aggCall.
+	private boolean isRolledUpColumnAllowedInAgg(SqlIdentifier identifier, SqlValidatorScope scope,
+		SqlCall aggCall, SqlNode parent) {
+		Pair<String, String> pair = findTableColumnPair(identifier, scope);
+
+		if (pair == null) {
+			return true;
+		}
+
+		String tableAlias = pair.left;
+		String columnName = pair.right;
+
+		Table table = findTable(tableAlias);
+		if (table != null) {
+			return table.rolledUpColumnValidInsideAgg(columnName, aggCall, parent,
+				catalogReader.getConfig());
+		}
+		return true;
+	}
+
+
+	// Returns true iff the given column is actually rolled up.
+	private boolean isRolledUpColumn(SqlIdentifier identifier, SqlValidatorScope scope) {
+		Pair<String, String> pair = findTableColumnPair(identifier, scope);
+
+		if (pair == null) {
+			return false;
+		}
+
+		String tableAlias = pair.left;
+		String columnName = pair.right;
+
+		Table table = findTable(tableAlias);
+		if (table != null) {
+			return table.isRolledUp(columnName);
+		}
+		return false;
+	}
+
+	private Table findTable(CalciteSchema schema, String tableName, boolean caseSensitive) {
+		CalciteSchema.TableEntry entry = schema.getTable(tableName, caseSensitive);
+		if (entry != null) {
+			return entry.getTable();
+		}
+
+		// Check sub schemas
+		for (CalciteSchema subSchema : schema.getSubSchemaMap().values()) {
+			Table table = findTable(subSchema, tableName, caseSensitive);
+			if (table != null) {
+				return table;
+			}
+		}
+
+		return null;
+	}
+
+	/**
+	 * Given a table alias, find the corresponding {@link Table} associated with it
+	 * */
+	private Table findTable(String alias) {
+		List<String> names = null;
+		if (tableScope == null) {
+			// no tables to find
+			return null;
+		}
+
+		for (ScopeChild child : tableScope.children) {
+			if (catalogReader.nameMatcher().matches(child.name, alias)) {
+				names = ((SqlIdentifier) child.namespace.getNode()).names;
+				break;
+			}
+		}
+		if (names == null || names.size() == 0) {
+			return null;
+		} else if (names.size() == 1) {
+			return findTable(catalogReader.getRootSchema(), names.get(0),
+				catalogReader.nameMatcher().isCaseSensitive());
+		}
+
+		CalciteSchema.TableEntry entry =
+			SqlValidatorUtil.getTableEntry(catalogReader, names);
+
+		return entry == null ? null : entry.getTable();
+	}
+
+	private boolean shouldCheckForRollUp(SqlNode from) {
+		if (from != null) {
+			SqlKind kind = stripAs(from).getKind();
+			return kind != SqlKind.VALUES && kind != SqlKind.SELECT;
+		}
+		return false;
+	}
+
+	/** Validates that a query can deliver the modality it promises. Only called
+	 * on the top-most SELECT or set operator in the tree. */
+	private void validateModality(SqlNode query) {
+		final SqlModality modality = deduceModality(query);
+		if (query instanceof SqlSelect) {
+			final SqlSelect select = (SqlSelect) query;
+			validateModality(select, modality, true);
+		} else if (query.getKind() == SqlKind.VALUES) {
+			switch (modality) {
+				case STREAM:
+					throw newValidationError(query, Static.RESOURCE.cannotStreamValues());
+			}
+		} else {
+			assert query.isA(SqlKind.SET_QUERY);
+			final SqlCall call = (SqlCall) query;
+			for (SqlNode operand : call.getOperandList()) {
+				if (deduceModality(operand) != modality) {
+					throw newValidationError(operand,
+						Static.RESOURCE.streamSetOpInconsistentInputs());
+				}
+				validateModality(operand);
+			}
+		}
+	}
+
+	/** Return the intended modality of a SELECT or set-op. */
+	private SqlModality deduceModality(SqlNode query) {
+		if (query instanceof SqlSelect) {
+			SqlSelect select = (SqlSelect) query;
+			return select.getModifierNode(SqlSelectKeyword.STREAM) != null
+				? SqlModality.STREAM
+				: SqlModality.RELATION;
+		} else if (query.getKind() == SqlKind.VALUES) {
+			return SqlModality.RELATION;
+		} else {
+			assert query.isA(SqlKind.SET_QUERY);
+			final SqlCall call = (SqlCall) query;
+			return deduceModality(call.getOperandList().get(0));
+		}
+	}
+
+	public boolean validateModality(SqlSelect select, SqlModality modality,
+		boolean fail) {
+		final SelectScope scope = getRawSelectScope(select);
+
+		switch (modality) {
+			case STREAM:
+				if (scope.children.size() == 1) {
+					for (ScopeChild child : scope.children) {
+						if (!child.namespace.supportsModality(modality)) {
+							if (fail) {
+								throw newValidationError(child.namespace.getNode(),
+									Static.RESOURCE.cannotConvertToStream(child.name));
+							} else {
+								return false;
+							}
+						}
+					}
+				} else {
+					int supportsModalityCount = 0;
+					for (ScopeChild child : scope.children) {
+						if (child.namespace.supportsModality(modality)) {
+							++supportsModalityCount;
+						}
+					}
+
+					if (supportsModalityCount == 0) {
+						if (fail) {
+							String inputs = String.join(", ", scope.getChildNames());
+							throw newValidationError(select,
+								Static.RESOURCE.cannotStreamResultsForNonStreamingInputs(inputs));
+						} else {
+							return false;
+						}
+					}
+				}
+				break;
+			default:
+				for (ScopeChild child : scope.children) {
+					if (!child.namespace.supportsModality(modality)) {
+						if (fail) {
+							throw newValidationError(child.namespace.getNode(),
+								Static.RESOURCE.cannotConvertToRelation(child.name));
+						} else {
+							return false;
+						}
+					}
+				}
+		}
+
+		// Make sure that aggregation is possible.
+		final SqlNode aggregateNode = getAggregate(select);
+		if (aggregateNode != null) {
+			switch (modality) {
+				case STREAM:
+					SqlNodeList groupList = select.getGroup();
+					if (groupList == null
+						|| !SqlValidatorUtil.containsMonotonic(scope, groupList)) {
+						if (fail) {
+							throw newValidationError(aggregateNode,
+								Static.RESOURCE.streamMustGroupByMonotonic());
+						} else {
+							return false;
+						}
+					}
+			}
+		}
+
+		// Make sure that ORDER BY is possible.
+		final SqlNodeList orderList  = select.getOrderList();
+		if (orderList != null && orderList.size() > 0) {
+			switch (modality) {
+				case STREAM:
+					if (!hasSortedPrefix(scope, orderList)) {
+						if (fail) {
+							throw newValidationError(orderList.get(0),
+								Static.RESOURCE.streamMustOrderByMonotonic());
+						} else {
+							return false;
+						}
+					}
+			}
+		}
+		return true;
+	}
+
+	/** Returns whether the prefix is sorted. */
+	private boolean hasSortedPrefix(SelectScope scope, SqlNodeList orderList) {
+		return isSortCompatible(scope, orderList.get(0), false);
+	}
+
+	private boolean isSortCompatible(SelectScope scope, SqlNode node,
+		boolean descending) {
+		switch (node.getKind()) {
+			case DESCENDING:
+				return isSortCompatible(scope, ((SqlCall) node).getOperandList().get(0),
+					true);
+		}
+		final SqlMonotonicity monotonicity = scope.getMonotonicity(node);
+		switch (monotonicity) {
+			case INCREASING:
+			case STRICTLY_INCREASING:
+				return !descending;
+			case DECREASING:
+			case STRICTLY_DECREASING:
+				return descending;
+			default:
+				return false;
+		}
+	}
+
+	protected void validateWindowClause(SqlSelect select) {
+		final SqlNodeList windowList = select.getWindowList();
+		@SuppressWarnings("unchecked") final List<SqlWindow> windows =
+			(List) windowList.getList();
+		if (windows.isEmpty()) {
+			return;
+		}
+
+		final SelectScope windowScope = (SelectScope) getFromScope(select);
+		assert windowScope != null;
+
+		// 1. ensure window names are simple
+		// 2. ensure they are unique within this scope
+		for (SqlWindow window : windows) {
+			SqlIdentifier declName = window.getDeclName();
+			if (!declName.isSimple()) {
+				throw newValidationError(declName, RESOURCE.windowNameMustBeSimple());
+			}
+
+			if (windowScope.existingWindowName(declName.toString())) {
+				throw newValidationError(declName, RESOURCE.duplicateWindowName());
+			} else {
+				windowScope.addWindowName(declName.toString());
+			}
+		}
+
+		// 7.10 rule 2
+		// Check for pairs of windows which are equivalent.
+		for (int i = 0; i < windows.size(); i++) {
+			SqlNode window1 = windows.get(i);
+			for (int j = i + 1; j < windows.size(); j++) {
+				SqlNode window2 = windows.get(j);
+				if (window1.equalsDeep(window2, Litmus.IGNORE)) {
+					throw newValidationError(window2, RESOURCE.dupWindowSpec());
+				}
+			}
+		}
+
+		for (SqlWindow window : windows) {
+			final SqlNodeList expandedOrderList =
+				(SqlNodeList) expand(window.getOrderList(), windowScope);
+			window.setOrderList(expandedOrderList);
+			expandedOrderList.validate(this, windowScope);
+
+			final SqlNodeList expandedPartitionList =
+				(SqlNodeList) expand(window.getPartitionList(), windowScope);
+			window.setPartitionList(expandedPartitionList);
+			expandedPartitionList.validate(this, windowScope);
+		}
+
+		// Hand off to validate window spec components
+		windowList.validate(this, windowScope);
+	}
+
+	public void validateWith(SqlWith with, SqlValidatorScope scope) {
+		final SqlValidatorNamespace namespace = getNamespace(with);
+		validateNamespace(namespace, unknownType);
+	}
+
+	public void validateWithItem(SqlWithItem withItem) {
+		if (withItem.columnList != null) {
+			final RelDataType rowType = getValidatedNodeType(withItem.query);
+			final int fieldCount = rowType.getFieldCount();
+			if (withItem.columnList.size() != fieldCount) {
+				throw newValidationError(withItem.columnList,
+					RESOURCE.columnCountMismatch());
+			}
+			SqlValidatorUtil.checkIdentifierListForDuplicates(
+				withItem.columnList.getList(), validationErrorFunction);
+		} else {
+			// Luckily, field names have not been make unique yet.
+			final List<String> fieldNames =
+				getValidatedNodeType(withItem.query).getFieldNames();
+			final int i = Util.firstDuplicate(fieldNames);
+			if (i >= 0) {
+				throw newValidationError(withItem.query,
+					RESOURCE.duplicateColumnAndNoColumnList(fieldNames.get(i)));
+			}
+		}
+	}
+
+	public void validateSequenceValue(SqlValidatorScope scope, SqlIdentifier id) {
+		// Resolve identifier as a table.
+		final SqlValidatorScope.ResolvedImpl resolved =
+			new SqlValidatorScope.ResolvedImpl();
+		scope.resolveTable(id.names, catalogReader.nameMatcher(),
+			SqlValidatorScope.Path.EMPTY, resolved);
+		if (resolved.count() != 1) {
+			throw newValidationError(id, RESOURCE.tableNameNotFound(id.toString()));
+		}
+		// We've found a table. But is it a sequence?
+		final SqlValidatorNamespace ns = resolved.only().namespace;
+		if (ns instanceof TableNamespace) {
+			final Table table = ns.getTable().unwrap(Table.class);
+			switch (table.getJdbcTableType()) {
+				case SEQUENCE:
+				case TEMPORARY_SEQUENCE:
+					return;
+			}
+		}
+		throw newValidationError(id, RESOURCE.notASequence(id.toString()));
+	}
+
+	public SqlValidatorScope getWithScope(SqlNode withItem) {
+		assert withItem.getKind() == SqlKind.WITH_ITEM;
+		return scopes.get(withItem);
+	}
+
+	/**
+	 * Validates the ORDER BY clause of a SELECT statement.
+	 *
+	 * @param select Select statement
+	 */
+	protected void validateOrderList(SqlSelect select) {
+		// ORDER BY is validated in a scope where aliases in the SELECT clause
+		// are visible. For example, "SELECT empno AS x FROM emp ORDER BY x"
+		// is valid.
+		SqlNodeList orderList = select.getOrderList();
+		if (orderList == null) {
+			return;
+		}
+		if (!shouldAllowIntermediateOrderBy()) {
+			if (!cursorSet.contains(select)) {
+				throw newValidationError(select, RESOURCE.invalidOrderByPos());
+			}
+		}
+		final SqlValidatorScope orderScope = getOrderScope(select);
+		Objects.requireNonNull(orderScope);
+
+		List<SqlNode> expandList = new ArrayList<>();
+		for (SqlNode orderItem : orderList) {
+			SqlNode expandedOrderItem = expand(orderItem, orderScope);
+			expandList.add(expandedOrderItem);
+		}
+
+		SqlNodeList expandedOrderList = new SqlNodeList(
+			expandList,
+			orderList.getParserPosition());
+		select.setOrderBy(expandedOrderList);
+
+		for (SqlNode orderItem : expandedOrderList) {
+			validateOrderItem(select, orderItem);
+		}
+	}
+
+	/**
+	 * Validates an item in the GROUP BY clause of a SELECT statement.
+	 *
+	 * @param select Select statement
+	 * @param groupByItem GROUP BY clause item
+	 */
+	private void validateGroupByItem(SqlSelect select, SqlNode groupByItem) {
+		final SqlValidatorScope groupByScope = getGroupScope(select);
+		groupByScope.validateExpr(groupByItem);
+	}
+
+	/**
+	 * Validates an item in the ORDER BY clause of a SELECT statement.
+	 *
+	 * @param select Select statement
+	 * @param orderItem ORDER BY clause item
+	 */
+	private void validateOrderItem(SqlSelect select, SqlNode orderItem) {
+		switch (orderItem.getKind()) {
+			case DESCENDING:
+				validateFeature(RESOURCE.sQLConformance_OrderByDesc(),
+					orderItem.getParserPosition());
+				validateOrderItem(select,
+					((SqlCall) orderItem).operand(0));
+				return;
+		}
+
+		final SqlValidatorScope orderScope = getOrderScope(select);
+		validateExpr(orderItem, orderScope);
+	}
+
+	public SqlNode expandOrderExpr(SqlSelect select, SqlNode orderExpr) {
+		final SqlNode newSqlNode =
+			new OrderExpressionExpander(select, orderExpr).go();
+		if (newSqlNode != orderExpr) {
+			final SqlValidatorScope scope = getOrderScope(select);
+			inferUnknownTypes(unknownType, scope, newSqlNode);
+			final RelDataType type = deriveType(scope, newSqlNode);
+			setValidatedNodeType(newSqlNode, type);
+		}
+		return newSqlNode;
+	}
+
+	/**
+	 * Validates the GROUP BY clause of a SELECT statement. This method is
+	 * called even if no GROUP BY clause is present.
+	 */
+	protected void validateGroupClause(SqlSelect select) {
+		SqlNodeList groupList = select.getGroup();
+		if (groupList == null) {
+			return;
+		}
+		final String clause = "GROUP BY";
+		validateNoAggs(aggOrOverFinder, groupList, clause);
+		final SqlValidatorScope groupScope = getGroupScope(select);
+		inferUnknownTypes(unknownType, groupScope, groupList);
+
+		// expand the expression in group list.
+		List<SqlNode> expandedList = new ArrayList<>();
+		for (SqlNode groupItem : groupList) {
+			SqlNode expandedItem = expandGroupByOrHavingExpr(groupItem, groupScope, select, false);
+			expandedList.add(expandedItem);
+		}
+		groupList = new SqlNodeList(expandedList, groupList.getParserPosition());
+		select.setGroupBy(groupList);
+		for (SqlNode groupItem : expandedList) {
+			validateGroupByItem(select, groupItem);
+		}
+
+		// Nodes in the GROUP BY clause are expressions except if they are calls
+		// to the GROUPING SETS, ROLLUP or CUBE operators; this operators are not
+		// expressions, because they do not have a type.
+		for (SqlNode node : groupList) {
+			switch (node.getKind()) {
+				case GROUPING_SETS:
+				case ROLLUP:
+				case CUBE:
+					node.validate(this, groupScope);
+					break;
+				default:
+					node.validateExpr(this, groupScope);
+			}
+		}
+
+		// Derive the type of each GROUP BY item. We don't need the type, but
+		// it resolves functions, and that is necessary for deducing
+		// monotonicity.
+		final SqlValidatorScope selectScope = getSelectScope(select);
+		AggregatingSelectScope aggregatingScope = null;
+		if (selectScope instanceof AggregatingSelectScope) {
+			aggregatingScope = (AggregatingSelectScope) selectScope;
+		}
+		for (SqlNode groupItem : groupList) {
+			if (groupItem instanceof SqlNodeList
+				&& ((SqlNodeList) groupItem).size() == 0) {
+				continue;
+			}
+			validateGroupItem(groupScope, aggregatingScope, groupItem);
+		}
+
+		SqlNode agg = aggFinder.findAgg(groupList);
+		if (agg != null) {
+			throw newValidationError(agg, RESOURCE.aggregateIllegalInClause(clause));
+		}
+	}
+
+	private void validateGroupItem(SqlValidatorScope groupScope,
+		AggregatingSelectScope aggregatingScope,
+		SqlNode groupItem) {
+		switch (groupItem.getKind()) {
+			case GROUPING_SETS:
+			case ROLLUP:
+			case CUBE:
+				validateGroupingSets(groupScope, aggregatingScope, (SqlCall) groupItem);
+				break;
+			default:
+				if (groupItem instanceof SqlNodeList) {
+					break;
+				}
+				final RelDataType type = deriveType(groupScope, groupItem);
+				setValidatedNodeType(groupItem, type);
+		}
+	}
+
+	private void validateGroupingSets(SqlValidatorScope groupScope,
+		AggregatingSelectScope aggregatingScope, SqlCall groupItem) {
+		for (SqlNode node : groupItem.getOperandList()) {
+			validateGroupItem(groupScope, aggregatingScope, node);
+		}
+	}
+
+	protected void validateWhereClause(SqlSelect select) {
+		// validate WHERE clause
+		final SqlNode where = select.getWhere();
+		if (where == null) {
+			return;
+		}
+		final SqlValidatorScope whereScope = getWhereScope(select);
+		final SqlNode expandedWhere = expand(where, whereScope);
+		select.setWhere(expandedWhere);
+		validateWhereOrOn(whereScope, expandedWhere, "WHERE");
+	}
+
+	protected void validateWhereOrOn(
+		SqlValidatorScope scope,
+		SqlNode condition,
+		String clause) {
+		validateNoAggs(aggOrOverOrGroupFinder, condition, clause);
+		inferUnknownTypes(
+			booleanType,
+			scope,
+			condition);
+		condition.validate(this, scope);
+
+		final RelDataType type = deriveType(scope, condition);
+		if (!SqlTypeUtil.inBooleanFamily(type)) {
+			throw newValidationError(condition, RESOURCE.condMustBeBoolean(clause));
+		}
+	}
+
+	protected void validateHavingClause(SqlSelect select) {
+		// HAVING is validated in the scope after groups have been created.
+		// For example, in "SELECT empno FROM emp WHERE empno = 10 GROUP BY
+		// deptno HAVING empno = 10", the reference to 'empno' in the HAVING
+		// clause is illegal.
+		SqlNode having = select.getHaving();
+		if (having == null) {
+			return;
+		}
+		final AggregatingScope havingScope =
+			(AggregatingScope) getSelectScope(select);
+		if (getConformance().isHavingAlias()) {
+			SqlNode newExpr = expandGroupByOrHavingExpr(having, havingScope, select, true);
+			if (having != newExpr) {
+				having = newExpr;
+				select.setHaving(newExpr);
+			}
+		}
+		havingScope.checkAggregateExpr(having, true);
+		inferUnknownTypes(
+			booleanType,
+			havingScope,
+			having);
+		having.validate(this, havingScope);
+		final RelDataType type = deriveType(havingScope, having);
+		if (!SqlTypeUtil.inBooleanFamily(type)) {
+			throw newValidationError(having, RESOURCE.havingMustBeBoolean());
+		}
+	}
+
+	protected RelDataType validateSelectList(
+		final SqlNodeList selectItems,
+		SqlSelect select,
+		RelDataType targetRowType) {
+		// First pass, ensure that aliases are unique. "*" and "TABLE.*" items
+		// are ignored.
+
+		// Validate SELECT list. Expand terms of the form "*" or "TABLE.*".
+		final SqlValidatorScope selectScope = getSelectScope(select);
+		final List<SqlNode> expandedSelectItems = new ArrayList<>();
+		final Set<String> aliases = new HashSet<>();
+		final List<Map.Entry<String, RelDataType>> fieldList = new ArrayList<>();
+
+		for (int i = 0; i < selectItems.size(); i++) {
+			SqlNode selectItem = selectItems.get(i);
+			if (selectItem instanceof SqlSelect) {
+				handleScalarSubQuery(
+					select,
+					(SqlSelect) selectItem,
+					expandedSelectItems,
+					aliases,
+					fieldList);
+			} else {
+				expandSelectItem(
+					selectItem,
+					select,
+					targetRowType.isStruct()
+						&& targetRowType.getFieldCount() >= i
+						? targetRowType.getFieldList().get(i).getType()
+						: unknownType,
+					expandedSelectItems,
+					aliases,
+					fieldList,
+					false);
+			}
+		}
+
+		// Create the new select list with expanded items.  Pass through
+		// the original parser position so that any overall failures can
+		// still reference the original input text.
+		SqlNodeList newSelectList =
+			new SqlNodeList(
+				expandedSelectItems,
+				selectItems.getParserPosition());
+		if (shouldExpandIdentifiers()) {
+			select.setSelectList(newSelectList);
+		}
+		getRawSelectScope(select).setExpandedSelectList(expandedSelectItems);
+
+		// TODO: when SELECT appears as a value sub-query, should be using
+		// something other than unknownType for targetRowType
+		inferUnknownTypes(targetRowType, selectScope, newSelectList);
+
+		for (SqlNode selectItem : expandedSelectItems) {
+			validateNoAggs(groupFinder, selectItem, "SELECT");
+			validateExpr(selectItem, selectScope);
+		}
+
+		return typeFactory.createStructType(fieldList);
+	}
+
+	/**
+	 * Validates an expression.
+	 *
+	 * @param expr  Expression
+	 * @param scope Scope in which expression occurs
+	 */
+	private void validateExpr(SqlNode expr, SqlValidatorScope scope) {
+		if (expr instanceof SqlCall) {
+			final SqlOperator op = ((SqlCall) expr).getOperator();
+			if (op.isAggregator() && op.requiresOver()) {
+				throw newValidationError(expr,
+					RESOURCE.absentOverClause());
+			}
+		}
+
+		// Call on the expression to validate itself.
+		expr.validateExpr(this, scope);
+
+		// Perform any validation specific to the scope. For example, an
+		// aggregating scope requires that expressions are valid aggregations.
+		scope.validateExpr(expr);
+	}
+
+	/**
+	 * Processes SubQuery found in Select list. Checks that is actually Scalar
+	 * sub-query and makes proper entries in each of the 3 lists used to create
+	 * the final rowType entry.
+	 *
+	 * @param parentSelect        base SqlSelect item
+	 * @param selectItem          child SqlSelect from select list
+	 * @param expandedSelectItems Select items after processing
+	 * @param aliasList           built from user or system values
+	 * @param fieldList           Built up entries for each select list entry
+	 */
+	private void handleScalarSubQuery(
+		SqlSelect parentSelect,
+		SqlSelect selectItem,
+		List<SqlNode> expandedSelectItems,
+		Set<String> aliasList,
+		List<Map.Entry<String, RelDataType>> fieldList) {
+		// A scalar sub-query only has one output column.
+		if (1 != selectItem.getSelectList().size()) {
+			throw newValidationError(selectItem,
+				RESOURCE.onlyScalarSubQueryAllowed());
+		}
+
+		// No expansion in this routine just append to list.
+		expandedSelectItems.add(selectItem);
+
+		// Get or generate alias and add to list.
+		final String alias =
+			deriveAlias(
+				selectItem,
+				aliasList.size());
+		aliasList.add(alias);
+
+		final SelectScope scope = (SelectScope) getWhereScope(parentSelect);
+		final RelDataType type = deriveType(scope, selectItem);
+		setValidatedNodeType(selectItem, type);
+
+		// we do not want to pass on the RelRecordType returned
+		// by the sub query.  Just the type of the single expression
+		// in the sub-query select list.
+		assert type instanceof RelRecordType;
+		RelRecordType rec = (RelRecordType) type;
+
+		RelDataType nodeType = rec.getFieldList().get(0).getType();
+		nodeType = typeFactory.createTypeWithNullability(nodeType, true);
+		fieldList.add(Pair.of(alias, nodeType));
+	}
+
+	/**
+	 * Derives a row-type for INSERT and UPDATE operations.
+	 *
+	 * @param table            Target table for INSERT/UPDATE
+	 * @param targetColumnList List of target columns, or null if not specified
+	 * @param append           Whether to append fields to those in <code>
+	 *                         baseRowType</code>
+	 * @return Rowtype
+	 */
+	protected RelDataType createTargetRowType(
+		SqlValidatorTable table,
+		SqlNodeList targetColumnList,
+		boolean append) {
+		RelDataType baseRowType = table.getRowType();
+		if (targetColumnList == null) {
+			return baseRowType;
+		}
+		List<RelDataTypeField> targetFields = baseRowType.getFieldList();
+		final List<Map.Entry<String, RelDataType>> fields = new ArrayList<>();
+		if (append) {
+			for (RelDataTypeField targetField : targetFields) {
+				fields.add(
+					Pair.of(SqlUtil.deriveAliasFromOrdinal(fields.size()),
+						targetField.getType()));
+			}
+		}
+		final Set<Integer> assignedFields = new HashSet<>();
+		final RelOptTable relOptTable = table instanceof RelOptTable
+			? ((RelOptTable) table) : null;
+		for (SqlNode node : targetColumnList) {
+			SqlIdentifier id = (SqlIdentifier) node;
+			RelDataTypeField targetField =
+				SqlValidatorUtil.getTargetField(
+					baseRowType, typeFactory, id, catalogReader, relOptTable);
+			if (targetField == null) {
+				throw newValidationError(id,
+					RESOURCE.unknownTargetColumn(id.toString()));
+			}
+			if (!assignedFields.add(targetField.getIndex())) {
+				throw newValidationError(id,
+					RESOURCE.duplicateTargetColumn(targetField.getName()));
+			}
+			fields.add(targetField);
+		}
+		return typeFactory.createStructType(fields);
+	}
+
+	public void validateInsert(SqlInsert insert) {
+		final SqlValidatorNamespace targetNamespace = getNamespace(insert);
+		validateNamespace(targetNamespace, unknownType);
+		final RelOptTable relOptTable = SqlValidatorUtil.getRelOptTable(
+			targetNamespace, catalogReader.unwrap(Prepare.CatalogReader.class), null, null);
+		final SqlValidatorTable table = relOptTable == null
+			? targetNamespace.getTable()
+			: relOptTable.unwrap(SqlValidatorTable.class);
+
+		// INSERT has an optional column name list.  If present then
+		// reduce the rowtype to the columns specified.  If not present
+		// then the entire target rowtype is used.
+		final RelDataType targetRowType =
+			createTargetRowType(
+				table,
+				insert.getTargetColumnList(),
+				false);
+
+		final SqlNode source = insert.getSource();
+		if (source instanceof SqlSelect) {
+			final SqlSelect sqlSelect = (SqlSelect) source;
+			validateSelect(sqlSelect, targetRowType);
+		} else {
+			final SqlValidatorScope scope = scopes.get(source);
+			validateQuery(source, scope, targetRowType);
+		}
+
+		// REVIEW jvs 4-Dec-2008: In FRG-365, this namespace row type is
+		// discarding the type inferred by inferUnknownTypes (which was invoked
+		// from validateSelect above).  It would be better if that information
+		// were used here so that we never saw any untyped nulls during
+		// checkTypeAssignment.
+		final RelDataType sourceRowType = getNamespace(source).getRowType();
+		final RelDataType logicalTargetRowType =
+			getLogicalTargetRowType(targetRowType, insert);
+		setValidatedNodeType(insert, logicalTargetRowType);
+		final RelDataType logicalSourceRowType =
+			getLogicalSourceRowType(sourceRowType, insert);
+
+		checkFieldCount(insert.getTargetTable(), table, source,
+			logicalSourceRowType, logicalTargetRowType);
+
+		checkTypeAssignment(logicalSourceRowType, logicalTargetRowType, insert);
+
+		checkConstraint(table, source, logicalTargetRowType);
+
+		validateAccess(insert.getTargetTable(), table, SqlAccessEnum.INSERT);
+	}
+
+	/**
+	 * Validates insert values against the constraint of a modifiable view.
+	 *
+	 * @param validatorTable Table that may wrap a ModifiableViewTable
+	 * @param source        The values being inserted
+	 * @param targetRowType The target type for the view
+	 */
+	private void checkConstraint(
+		SqlValidatorTable validatorTable,
+		SqlNode source,
+		RelDataType targetRowType) {
+		final ModifiableViewTable modifiableViewTable =
+			validatorTable.unwrap(ModifiableViewTable.class);
+		if (modifiableViewTable != null && source instanceof SqlCall) {
+			final Table table = modifiableViewTable.unwrap(Table.class);
+			final RelDataType tableRowType = table.getRowType(typeFactory);
+			final List<RelDataTypeField> tableFields = tableRowType.getFieldList();
+
+			// Get the mapping from column indexes of the underlying table
+			// to the target columns and view constraints.
+			final Map<Integer, RelDataTypeField> tableIndexToTargetField =
+				SqlValidatorUtil.getIndexToFieldMap(tableFields, targetRowType);
+			final Map<Integer, RexNode> projectMap =
+				RelOptUtil.getColumnConstraints(modifiableViewTable, targetRowType, typeFactory);
+
+			// Determine columns (indexed to the underlying table) that need
+			// to be validated against the view constraint.
+			final ImmutableBitSet targetColumns =
+				ImmutableBitSet.of(tableIndexToTargetField.keySet());
+			final ImmutableBitSet constrainedColumns =
+				ImmutableBitSet.of(projectMap.keySet());
+			final ImmutableBitSet constrainedTargetColumns =
+				targetColumns.intersect(constrainedColumns);
+
+			// Validate insert values against the view constraint.
+			final List<SqlNode> values = ((SqlCall) source).getOperandList();
+			for (final int colIndex : constrainedTargetColumns.asList()) {
+				final String colName = tableFields.get(colIndex).getName();
+				final RelDataTypeField targetField = tableIndexToTargetField.get(colIndex);
+				for (SqlNode row : values) {
+					final SqlCall call = (SqlCall) row;
+					final SqlNode sourceValue = call.operand(targetField.getIndex());
+					final ValidationError validationError =
+						new ValidationError(sourceValue,
+							RESOURCE.viewConstraintNotSatisfied(colName,
+								Util.last(validatorTable.getQualifiedName())));
+					RelOptUtil.validateValueAgainstConstraint(sourceValue,
+						projectMap.get(colIndex), validationError);
+				}
+			}
+		}
+	}
+
+	/**
+	 * Validates updates against the constraint of a modifiable view.
+	 *
+	 * @param validatorTable A {@link SqlValidatorTable} that may wrap a
+	 *                       ModifiableViewTable
+	 * @param update         The UPDATE parse tree node
+	 * @param targetRowType  The target type
+	 */
+	private void checkConstraint(
+		SqlValidatorTable validatorTable,
+		SqlUpdate update,
+		RelDataType targetRowType) {
+		final ModifiableViewTable modifiableViewTable =
+			validatorTable.unwrap(ModifiableViewTable.class);
+		if (modifiableViewTable != null) {
+			final Table table = modifiableViewTable.unwrap(Table.class);
+			final RelDataType tableRowType = table.getRowType(typeFactory);
+
+			final Map<Integer, RexNode> projectMap =
+				RelOptUtil.getColumnConstraints(modifiableViewTable, targetRowType,
+					typeFactory);
+			final Map<String, Integer> nameToIndex =
+				SqlValidatorUtil.mapNameToIndex(tableRowType.getFieldList());
+
+			// Validate update values against the view constraint.
+			final List<SqlNode> targets = update.getTargetColumnList().getList();
+			final List<SqlNode> sources = update.getSourceExpressionList().getList();
+			for (final Pair<SqlNode, SqlNode> column : Pair.zip(targets, sources)) {
+				final String columnName = ((SqlIdentifier) column.left).getSimple();
+				final Integer columnIndex = nameToIndex.get(columnName);
+				if (projectMap.containsKey(columnIndex)) {
+					final RexNode columnConstraint = projectMap.get(columnIndex);
+					final ValidationError validationError =
+						new ValidationError(column.right,
+							RESOURCE.viewConstraintNotSatisfied(columnName,
+								Util.last(validatorTable.getQualifiedName())));
+					RelOptUtil.validateValueAgainstConstraint(column.right,
+						columnConstraint, validationError);
+				}
+			}
+		}
+	}
+
+	private void checkFieldCount(SqlNode node, SqlValidatorTable table,
+		SqlNode source, RelDataType logicalSourceRowType,
+		RelDataType logicalTargetRowType) {
+		final int sourceFieldCount = logicalSourceRowType.getFieldCount();
+		final int targetFieldCount = logicalTargetRowType.getFieldCount();
+		if (sourceFieldCount != targetFieldCount) {
+			throw newValidationError(node,
+				RESOURCE.unmatchInsertColumn(targetFieldCount, sourceFieldCount));
+		}
+		// Ensure that non-nullable fields are targeted.
+		final InitializerContext rexBuilder =
+			new InitializerContext() {
+				public RexBuilder getRexBuilder() {
+					return new RexBuilder(typeFactory);
+				}
+
+				public RexNode convertExpression(SqlNode e) {
+					throw new UnsupportedOperationException();
+				}
+			};
+		final List<ColumnStrategy> strategies =
+			table.unwrap(RelOptTable.class).getColumnStrategies();
+		for (final RelDataTypeField field : table.getRowType().getFieldList()) {
+			final RelDataTypeField targetField =
+				logicalTargetRowType.getField(field.getName(), true, false);
+			switch (strategies.get(field.getIndex())) {
+				case NOT_NULLABLE:
+					assert !field.getType().isNullable();
+					if (targetField == null) {
+						throw newValidationError(node,
+							RESOURCE.columnNotNullable(field.getName()));
+					}
+					break;
+				case NULLABLE:
+					assert field.getType().isNullable();
+					break;
+				case VIRTUAL:
+				case STORED:
+					if (targetField != null
+						&& !isValuesWithDefault(source, targetField.getIndex())) {
+						throw newValidationError(node,
+							RESOURCE.insertIntoAlwaysGenerated(field.getName()));
+					}
+			}
+		}
+	}
+
+	/** Returns whether a query uses {@code DEFAULT} to populate a given
+	 *  column. */
+	private boolean isValuesWithDefault(SqlNode source, int column) {
+		switch (source.getKind()) {
+			case VALUES:
+				for (SqlNode operand : ((SqlCall) source).getOperandList()) {
+					if (!isRowWithDefault(operand, column)) {
+						return false;
+					}
+				}
+				return true;
+		}
+		return false;
+	}
+
+	private boolean isRowWithDefault(SqlNode operand, int column) {
+		switch (operand.getKind()) {
+			case ROW:
+				final SqlCall row = (SqlCall) operand;
+				return row.getOperandList().size() >= column
+					&& row.getOperandList().get(column).getKind() == SqlKind.DEFAULT;
+		}
+		return false;
+	}
+
+	protected RelDataType getLogicalTargetRowType(
+		RelDataType targetRowType,
+		SqlInsert insert) {
+		if (insert.getTargetColumnList() == null
+			&& conformance.isInsertSubsetColumnsAllowed()) {
+			// Target an implicit subset of columns.
+			final SqlNode source = insert.getSource();
+			final RelDataType sourceRowType = getNamespace(source).getRowType();
+			final RelDataType logicalSourceRowType =
+				getLogicalSourceRowType(sourceRowType, insert);
+			final RelDataType implicitTargetRowType =
+				typeFactory.createStructType(
+					targetRowType.getFieldList()
+						.subList(0, logicalSourceRowType.getFieldCount()));
+			final SqlValidatorNamespace targetNamespace = getNamespace(insert);
+			validateNamespace(targetNamespace, implicitTargetRowType);
+			return implicitTargetRowType;
+		} else {
+			// Either the set of columns are explicitly targeted, or target the full
+			// set of columns.
+			return targetRowType;
+		}
+	}
+
+	protected RelDataType getLogicalSourceRowType(
+		RelDataType sourceRowType,
+		SqlInsert insert) {
+		return sourceRowType;
+	}
+
+	protected void checkTypeAssignment(
+		RelDataType sourceRowType,
+		RelDataType targetRowType,
+		final SqlNode query) {
+		// NOTE jvs 23-Feb-2006: subclasses may allow for extra targets
+		// representing system-maintained columns, so stop after all sources
+		// matched
+		List<RelDataTypeField> sourceFields = sourceRowType.getFieldList();
+		List<RelDataTypeField> targetFields = targetRowType.getFieldList();
+		final int sourceCount = sourceFields.size();
+		for (int i = 0; i < sourceCount; ++i) {
+			RelDataType sourceType = sourceFields.get(i).getType();
+			RelDataType targetType = targetFields.get(i).getType();
+			if (!SqlTypeUtil.canAssignFrom(targetType, sourceType)) {
+				// FRG-255:  account for UPDATE rewrite; there's
+				// probably a better way to do this.
+				int iAdjusted = i;
+				if (query instanceof SqlUpdate) {
+					int nUpdateColumns =
+						((SqlUpdate) query).getTargetColumnList().size();
+					assert sourceFields.size() >= nUpdateColumns;
+					iAdjusted -= sourceFields.size() - nUpdateColumns;
+				}
+				SqlNode node = getNthExpr(query, iAdjusted, sourceCount);
+				String targetTypeString;
+				String sourceTypeString;
+				if (SqlTypeUtil.areCharacterSetsMismatched(
+					sourceType,
+					targetType)) {
+					sourceTypeString = sourceType.getFullTypeString();
+					targetTypeString = targetType.getFullTypeString();
+				} else {
+					sourceTypeString = sourceType.toString();
+					targetTypeString = targetType.toString();
+				}
+				throw newValidationError(node,
+					RESOURCE.typeNotAssignable(
+						targetFields.get(i).getName(), targetTypeString,
+						sourceFields.get(i).getName(), sourceTypeString));
+			}
+		}
+	}
+
+	/**
+	 * Locates the n'th expression in an INSERT or UPDATE query.
+	 *
+	 * @param query       Query
+	 * @param ordinal     Ordinal of expression
+	 * @param sourceCount Number of expressions
+	 * @return Ordinal'th expression, never null
+	 */
+	private SqlNode getNthExpr(SqlNode query, int ordinal, int sourceCount) {
+		if (query instanceof SqlInsert) {
+			SqlInsert insert = (SqlInsert) query;
+			if (insert.getTargetColumnList() != null) {
+				return insert.getTargetColumnList().get(ordinal);
+			} else {
+				return getNthExpr(
+					insert.getSource(),
+					ordinal,
+					sourceCount);
+			}
+		} else if (query instanceof SqlUpdate) {
+			SqlUpdate update = (SqlUpdate) query;
+			if (update.getTargetColumnList() != null) {
+				return update.getTargetColumnList().get(ordinal);
+			} else if (update.getSourceExpressionList() != null) {
+				return update.getSourceExpressionList().get(ordinal);
+			} else {
+				return getNthExpr(
+					update.getSourceSelect(),
+					ordinal,
+					sourceCount);
+			}
+		} else if (query instanceof SqlSelect) {
+			SqlSelect select = (SqlSelect) query;
+			if (select.getSelectList().size() == sourceCount) {
+				return select.getSelectList().get(ordinal);
+			} else {
+				return query; // give up
+			}
+		} else {
+			return query; // give up
+		}
+	}
+
+	public void validateDelete(SqlDelete call) {
+		final SqlSelect sqlSelect = call.getSourceSelect();
+		validateSelect(sqlSelect, unknownType);
+
+		final SqlValidatorNamespace targetNamespace = getNamespace(call);
+		validateNamespace(targetNamespace, unknownType);
+		final SqlValidatorTable table = targetNamespace.getTable();
+
+		validateAccess(call.getTargetTable(), table, SqlAccessEnum.DELETE);
+	}
+
+	public void validateUpdate(SqlUpdate call) {
+		final SqlValidatorNamespace targetNamespace = getNamespace(call);
+		validateNamespace(targetNamespace, unknownType);
+		final RelOptTable relOptTable = SqlValidatorUtil.getRelOptTable(
+			targetNamespace, catalogReader.unwrap(Prepare.CatalogReader.class), null, null);
+		final SqlValidatorTable table = relOptTable == null
+			? targetNamespace.getTable()
+			: relOptTable.unwrap(SqlValidatorTable.class);
+
+		final RelDataType targetRowType =
+			createTargetRowType(
+				table,
+				call.getTargetColumnList(),
+				true);
+
+		final SqlSelect select = call.getSourceSelect();
+		validateSelect(select, targetRowType);
+
+		final RelDataType sourceRowType = getNamespace(call).getRowType();
+		checkTypeAssignment(sourceRowType, targetRowType, call);
+
+		checkConstraint(table, call, targetRowType);
+
+		validateAccess(call.getTargetTable(), table, SqlAccessEnum.UPDATE);
+	}
+
+	public void validateMerge(SqlMerge call) {
+		SqlSelect sqlSelect = call.getSourceSelect();
+		// REVIEW zfong 5/25/06 - Does an actual type have to be passed into
+		// validateSelect()?
+
+		// REVIEW jvs 6-June-2006:  In general, passing unknownType like
+		// this means we won't be able to correctly infer the types
+		// for dynamic parameter markers (SET x = ?).  But
+		// maybe validateUpdate and validateInsert below will do
+		// the job?
+
+		// REVIEW ksecretan 15-July-2011: They didn't get a chance to
+		// since validateSelect() would bail.
+		// Let's use the update/insert targetRowType when available.
+		IdentifierNamespace targetNamespace =
+			(IdentifierNamespace) getNamespace(call.getTargetTable());
+		validateNamespace(targetNamespace, unknownType);
+
+		SqlValidatorTable table = targetNamespace.getTable();
+		validateAccess(call.getTargetTable(), table, SqlAccessEnum.UPDATE);
+
+		RelDataType targetRowType = unknownType;
+
+		if (call.getUpdateCall() != null) {
+			targetRowType = createTargetRowType(
+				table,
+				call.getUpdateCall().getTargetColumnList(),
+				true);
+		}
+		if (call.getInsertCall() != null) {
+			targetRowType = createTargetRowType(
+				table,
+				call.getInsertCall().getTargetColumnList(),
+				false);
+		}
+
+		validateSelect(sqlSelect, targetRowType);
+
+		if (call.getUpdateCall() != null) {
+			validateUpdate(call.getUpdateCall());
+		}
+		if (call.getInsertCall() != null) {
+			validateInsert(call.getInsertCall());
+		}
+	}
+
+	/**
+	 * Validates access to a table.
+	 *
+	 * @param table          Table
+	 * @param requiredAccess Access requested on table
+	 */
+	private void validateAccess(
+		SqlNode node,
+		SqlValidatorTable table,
+		SqlAccessEnum requiredAccess) {
+		if (table != null) {
+			SqlAccessType access = table.getAllowedAccess();
+			if (!access.allowsAccess(requiredAccess)) {
+				throw newValidationError(node,
+					RESOURCE.accessNotAllowed(requiredAccess.name(),
+						table.getQualifiedName().toString()));
+			}
+		}
+	}
+
+	/**
+	 * Validates a VALUES clause.
+	 *
+	 * @param node          Values clause
+	 * @param targetRowType Row type which expression must conform to
+	 * @param scope         Scope within which clause occurs
+	 */
+	protected void validateValues(
+		SqlCall node,
+		RelDataType targetRowType,
+		final SqlValidatorScope scope) {
+		assert node.getKind() == SqlKind.VALUES;
+
+		final List<SqlNode> operands = node.getOperandList();
+		for (SqlNode operand : operands) {
+			if (!(operand.getKind() == SqlKind.ROW)) {
+				throw Util.needToImplement(
+					"Values function where operands are scalars");
+			}
+
+			SqlCall rowConstructor = (SqlCall) operand;
+			if (conformance.isInsertSubsetColumnsAllowed() && targetRowType.isStruct()
+				&& rowConstructor.operandCount() < targetRowType.getFieldCount()) {
+				targetRowType =
+					typeFactory.createStructType(
+						targetRowType.getFieldList()
+							.subList(0, rowConstructor.operandCount()));
+			} else if (targetRowType.isStruct()
+				&& rowConstructor.operandCount() != targetRowType.getFieldCount()) {
+				return;
+			}
+
+			inferUnknownTypes(
+				targetRowType,
+				scope,
+				rowConstructor);
+
+			if (targetRowType.isStruct()) {
+				for (Pair<SqlNode, RelDataTypeField> pair
+					: Pair.zip(rowConstructor.getOperandList(),
+					targetRowType.getFieldList())) {
+					if (!pair.right.getType().isNullable()
+						&& SqlUtil.isNullLiteral(pair.left, false)) {
+						throw newValidationError(node,
+							RESOURCE.columnNotNullable(pair.right.getName()));
+					}
+				}
+			}
+		}
+
+		for (SqlNode operand : operands) {
+			operand.validate(this, scope);
+		}
+
+		// validate that all row types have the same number of columns
+		//  and that expressions in each column are compatible.
+		// A values expression is turned into something that looks like
+		// ROW(type00, type01,...), ROW(type11,...),...
+		final int rowCount = operands.size();
+		if (rowCount >= 2) {
+			SqlCall firstRow = (SqlCall) operands.get(0);
+			final int columnCount = firstRow.operandCount();
+
+			// 1. check that all rows have the same cols length
+			for (SqlNode operand : operands) {
+				SqlCall thisRow = (SqlCall) operand;
+				if (columnCount != thisRow.operandCount()) {
+					throw newValidationError(node,
+						RESOURCE.incompatibleValueType(
+							SqlStdOperatorTable.VALUES.getName()));
+				}
+			}
+
+			// 2. check if types at i:th position in each row are compatible
+			for (int col = 0; col < columnCount; col++) {
+				final int c = col;
+				final RelDataType type =
+					typeFactory.leastRestrictive(
+						new AbstractList<RelDataType>() {
+							public RelDataType get(int row) {
+								SqlCall thisRow = (SqlCall) operands.get(row);
+								return deriveType(scope, thisRow.operand(c));
+							}
+
+							public int size() {
+								return rowCount;
+							}
+						});
+
+				if (null == type) {
+					throw newValidationError(node,
+						RESOURCE.incompatibleValueType(
+							SqlStdOperatorTable.VALUES.getName()));
+				}
+			}
+		}
+	}
+
+	public void validateDataType(SqlDataTypeSpec dataType) {
+	}
+
+	public void validateDynamicParam(SqlDynamicParam dynamicParam) {
+	}
+
+	/**
+	 * Throws a validator exception with access to the validator context.
+	 * The exception is determined when an instance is created.
+	 */
+	private class ValidationError implements Supplier<CalciteContextException> {
+		private final SqlNode sqlNode;
+		private final Resources.ExInst<SqlValidatorException> validatorException;
+
+		ValidationError(SqlNode sqlNode,
+			Resources.ExInst<SqlValidatorException> validatorException) {
+			this.sqlNode = sqlNode;
+			this.validatorException = validatorException;
+		}
+
+		public CalciteContextException get() {
+			return newValidationError(sqlNode, validatorException);
+		}
+	}
+
+	/**
+	 * Throws a validator exception with access to the validator context.
+	 * The exception is determined when the function is applied.
+	 */
+	class ValidationErrorFunction
+		implements Function2<SqlNode, Resources.ExInst<SqlValidatorException>,
+		CalciteContextException> {
+		@Override public CalciteContextException apply(
+			SqlNode v0, Resources.ExInst<SqlValidatorException> v1) {
+			return newValidationError(v0, v1);
+		}
+	}
+
+	public ValidationErrorFunction getValidationErrorFunction() {
+		return validationErrorFunction;
+	}
+
+	public CalciteContextException newValidationError(SqlNode node,
+		Resources.ExInst<SqlValidatorException> e) {
+		assert node != null;
+		final SqlParserPos pos = node.getParserPosition();
+		return SqlUtil.newContextException(pos, e);
+	}
+
+	protected SqlWindow getWindowByName(
+		SqlIdentifier id,
+		SqlValidatorScope scope) {
+		SqlWindow window = null;
+		if (id.isSimple()) {
+			final String name = id.getSimple();
+			window = scope.lookupWindow(name);
+		}
+		if (window == null) {
+			throw newValidationError(id, RESOURCE.windowNotFound(id.toString()));
+		}
+		return window;
+	}
+
+	public SqlWindow resolveWindow(
+		SqlNode windowOrRef,
+		SqlValidatorScope scope,
+		boolean populateBounds) {
+		SqlWindow window;
+		if (windowOrRef instanceof SqlIdentifier) {
+			window = getWindowByName((SqlIdentifier) windowOrRef, scope);
+		} else {
+			window = (SqlWindow) windowOrRef;
+		}
+		while (true) {
+			final SqlIdentifier refId = window.getRefName();
+			if (refId == null) {
+				break;
+			}
+			final String refName = refId.getSimple();
+			SqlWindow refWindow = scope.lookupWindow(refName);
+			if (refWindow == null) {
+				throw newValidationError(refId, RESOURCE.windowNotFound(refName));
+			}
+			window = window.overlay(refWindow, this);
+		}
+
+		if (populateBounds) {
+			window.populateBounds();
+		}
+		return window;
+	}
+
+	public SqlNode getOriginal(SqlNode expr) {
+		SqlNode original = originalExprs.get(expr);
+		if (original == null) {
+			original = expr;
+		}
+		return original;
+	}
+
+	public void setOriginal(SqlNode expr, SqlNode original) {
+		// Don't overwrite the original original.
+		if (originalExprs.get(expr) == null) {
+			originalExprs.put(expr, original);
+		}
+	}
+
+	SqlValidatorNamespace lookupFieldNamespace(RelDataType rowType, String name) {
+		final SqlNameMatcher nameMatcher = catalogReader.nameMatcher();
+		final RelDataTypeField field = nameMatcher.field(rowType, name);
+		return new FieldNamespace(this, field.getType());
+	}
+
+	public void validateWindow(
+		SqlNode windowOrId,
+		SqlValidatorScope scope,
+		SqlCall call) {
+		// Enable nested aggregates with window aggregates (OVER operator)
+		inWindow = true;
+
+		final SqlWindow targetWindow;
+		switch (windowOrId.getKind()) {
+			case IDENTIFIER:
+				// Just verify the window exists in this query.  It will validate
+				// when the definition is processed
+				targetWindow = getWindowByName((SqlIdentifier) windowOrId, scope);
+				break;
+			case WINDOW:
+				targetWindow = (SqlWindow) windowOrId;
+				break;
+			default:
+				throw Util.unexpected(windowOrId.getKind());
+		}
+
+		assert targetWindow.getWindowCall() == null;
+		targetWindow.setWindowCall(call);
+		targetWindow.validate(this, scope);
+		targetWindow.setWindowCall(null);
+		call.validate(this, scope);
+
+		validateAggregateParams(call, null, scope);
+
+		// Disable nested aggregates post validation
+		inWindow = false;
+	}
+
+	@Override public void validateMatchRecognize(SqlCall call) {
+		final SqlMatchRecognize matchRecognize = (SqlMatchRecognize) call;
+		final MatchRecognizeScope scope =
+			(MatchRecognizeScope) getMatchRecognizeScope(matchRecognize);
+
+		final MatchRecognizeNamespace ns =
+			getNamespace(call).unwrap(MatchRecognizeNamespace.class);
+		assert ns.rowType == null;
+
+		// rows per match
+		final SqlLiteral rowsPerMatch = matchRecognize.getRowsPerMatch();
+		final boolean allRows = rowsPerMatch != null
+			&& rowsPerMatch.getValue()
+			== SqlMatchRecognize.RowsPerMatchOption.ALL_ROWS;
+
+		final RelDataTypeFactory.Builder typeBuilder = typeFactory.builder();
+
+		// parse PARTITION BY column
+		SqlNodeList partitionBy = matchRecognize.getPartitionList();
+		if (partitionBy != null) {
+			for (SqlNode node : partitionBy) {
+				SqlIdentifier identifier = (SqlIdentifier) node;
+				identifier.validate(this, scope);
+				RelDataType type = deriveType(scope, identifier);
+				String name = identifier.names.get(1);
+				typeBuilder.add(name, type);
+			}
+		}
+
+		// parse ORDER BY column
+		SqlNodeList orderBy = matchRecognize.getOrderList();
+		if (orderBy != null) {
+			for (SqlNode node : orderBy) {
+				node.validate(this, scope);
+				SqlIdentifier identifier = null;
+				if (node instanceof SqlBasicCall) {
+					identifier = (SqlIdentifier) ((SqlBasicCall) node).getOperands()[0];
+				} else {
+					identifier = (SqlIdentifier) node;
+				}
+
+				if (allRows) {
+					RelDataType type = deriveType(scope, identifier);
+					String name = identifier.names.get(1);
+					if (!typeBuilder.nameExists(name)) {
+						typeBuilder.add(name, type);
+					}
+				}
+			}
+		}
+
+		if (allRows) {
+			final SqlValidatorNamespace sqlNs =
+				getNamespace(matchRecognize.getTableRef());
+			final RelDataType inputDataType = sqlNs.getRowType();
+			for (RelDataTypeField fs : inputDataType.getFieldList()) {
+				if (!typeBuilder.nameExists(fs.getName())) {
+					typeBuilder.add(fs);
+				}
+			}
+		}
+
+		// retrieve pattern variables used in pattern and subset
+		SqlNode pattern = matchRecognize.getPattern();
+		PatternVarVisitor visitor = new PatternVarVisitor(scope);
+		pattern.accept(visitor);
+
+		SqlLiteral interval = matchRecognize.getInterval();
+		if (interval != null) {
+			interval.validate(this, scope);
+			if (((SqlIntervalLiteral) interval).signum() < 0) {
+				throw newValidationError(interval,
+					RESOURCE.intervalMustBeNonNegative(interval.toValue()));
+			}
+			if (orderBy == null || orderBy.size() == 0) {
+				throw newValidationError(interval,
+					RESOURCE.cannotUseWithinWithoutOrderBy());
+			}
+
+			SqlNode firstOrderByColumn = orderBy.getList().get(0);
+			SqlIdentifier identifier;
+			if (firstOrderByColumn instanceof SqlBasicCall) {
+				identifier = (SqlIdentifier) ((SqlBasicCall) firstOrderByColumn).getOperands()[0];
+			} else {
+				identifier = (SqlIdentifier) firstOrderByColumn;
+			}
+			RelDataType firstOrderByColumnType = deriveType(scope, identifier);
+			if (firstOrderByColumnType.getSqlTypeName() != SqlTypeName.TIMESTAMP) {
+				throw newValidationError(interval,
+					RESOURCE.firstColumnOfOrderByMustBeTimestamp());
+			}
+
+			SqlNode expand = expand(interval, scope);
+			RelDataType type = deriveType(scope, expand);
+			setValidatedNodeType(interval, type);
+		}
+
+		validateDefinitions(matchRecognize, scope);
+
+		SqlNodeList subsets = matchRecognize.getSubsetList();
+		if (subsets != null && subsets.size() > 0) {
+			for (SqlNode node : subsets) {
+				List<SqlNode> operands = ((SqlCall) node).getOperandList();
+				String leftString = ((SqlIdentifier) operands.get(0)).getSimple();
+				if (scope.getPatternVars().contains(leftString)) {
+					throw newValidationError(operands.get(0),
+						RESOURCE.patternVarAlreadyDefined(leftString));
+				}
+				scope.addPatternVar(leftString);
+				for (SqlNode right : (SqlNodeList) operands.get(1)) {
+					SqlIdentifier id = (SqlIdentifier) right;
+					if (!scope.getPatternVars().contains(id.getSimple())) {
+						throw newValidationError(id,
+							RESOURCE.unknownPattern(id.getSimple()));
+					}
+					scope.addPatternVar(id.getSimple());
+				}
+			}
+		}
+
+		// validate AFTER ... SKIP TO
+		final SqlNode skipTo = matchRecognize.getAfter();
+		if (skipTo instanceof SqlCall) {
+			final SqlCall skipToCall = (SqlCall) skipTo;
+			final SqlIdentifier id = skipToCall.operand(0);
+			if (!scope.getPatternVars().contains(id.getSimple())) {
+				throw newValidationError(id,
+					RESOURCE.unknownPattern(id.getSimple()));
+			}
+		}
+
+		List<Map.Entry<String, RelDataType>> measureColumns =
+			validateMeasure(matchRecognize, scope, allRows);
+		for (Map.Entry<String, RelDataType> c : measureColumns) {
+			if (!typeBuilder.nameExists(c.getKey())) {
+				typeBuilder.add(c.getKey(), c.getValue());
+			}
+		}
+
+		final RelDataType rowType = typeBuilder.build();
+		if (matchRecognize.getMeasureList().size() == 0) {
+			ns.setType(getNamespace(matchRecognize.getTableRef()).getRowType());
+		} else {
+			ns.setType(rowType);
+		}
+	}
+
+	private List<Map.Entry<String, RelDataType>> validateMeasure(SqlMatchRecognize mr,
+		MatchRecognizeScope scope, boolean allRows) {
+		final List<String> aliases = new ArrayList<>();
+		final List<SqlNode> sqlNodes = new ArrayList<>();
+		final SqlNodeList measures = mr.getMeasureList();
+		final List<Map.Entry<String, RelDataType>> fields = new ArrayList<>();
+
+		for (SqlNode measure : measures) {
+			assert measure instanceof SqlCall;
+			final String alias = deriveAlias(measure, aliases.size());
+			aliases.add(alias);
+
+			SqlNode expand = expand(measure, scope);
+			expand = navigationInMeasure(expand, allRows);
+			setOriginal(expand, measure);
+
+			inferUnknownTypes(unknownType, scope, expand);
+			final RelDataType type = deriveType(scope, expand);
+			setValidatedNodeType(measure, type);
+
+			fields.add(Pair.of(alias, type));
+			sqlNodes.add(
+				SqlStdOperatorTable.AS.createCall(SqlParserPos.ZERO, expand,
+					new SqlIdentifier(alias, SqlParserPos.ZERO)));
+		}
+
+		SqlNodeList list = new SqlNodeList(sqlNodes, measures.getParserPosition());
+		inferUnknownTypes(unknownType, scope, list);
+
+		for (SqlNode node : list) {
+			validateExpr(node, scope);
+		}
+
+		mr.setOperand(SqlMatchRecognize.OPERAND_MEASURES, list);
+
+		return fields;
+	}
+
+	private SqlNode navigationInMeasure(SqlNode node, boolean allRows) {
+		final Set<String> prefix = node.accept(new PatternValidator(true));
+		Util.discard(prefix);
+		final List<SqlNode> ops = ((SqlCall) node).getOperandList();
+
+		final SqlOperator defaultOp =
+			allRows ? SqlStdOperatorTable.RUNNING : SqlStdOperatorTable.FINAL;
+		final SqlNode op0 = ops.get(0);
+		if (!isRunningOrFinal(op0.getKind())
+			|| !allRows && op0.getKind() == SqlKind.RUNNING) {
+			SqlNode newNode = defaultOp.createCall(SqlParserPos.ZERO, op0);
+			node = SqlStdOperatorTable.AS.createCall(SqlParserPos.ZERO, newNode, ops.get(1));
+		}
+
+		node = new NavigationExpander().go(node);
+		return node;
+	}
+
+	private void validateDefinitions(SqlMatchRecognize mr,
+		MatchRecognizeScope scope) {
+		final Set<String> aliases = catalogReader.nameMatcher().createSet();
+		for (SqlNode item : mr.getPatternDefList().getList()) {
+			final String alias = alias(item);
+			if (!aliases.add(alias)) {
+				throw newValidationError(item,
+					Static.RESOURCE.patternVarAlreadyDefined(alias));
+			}
+			scope.addPatternVar(alias);
+		}
+
+		final List<SqlNode> sqlNodes = new ArrayList<>();
+		for (SqlNode item : mr.getPatternDefList().getList()) {
+			final String alias = alias(item);
+			SqlNode expand = expand(item, scope);
+			expand = navigationInDefine(expand, alias);
+			setOriginal(expand, item);
+
+			inferUnknownTypes(booleanType, scope, expand);
+			expand.validate(this, scope);
+
+			// Some extra work need required here.
+			// In PREV, NEXT, FINAL and LAST, only one pattern variable is allowed.
+			sqlNodes.add(
+				SqlStdOperatorTable.AS.createCall(SqlParserPos.ZERO, expand,
+					new SqlIdentifier(alias, SqlParserPos.ZERO)));
+
+			final RelDataType type = deriveType(scope, expand);
+			if (!SqlTypeUtil.inBooleanFamily(type)) {
+				throw newValidationError(expand, RESOURCE.condMustBeBoolean("DEFINE"));
+			}
+			setValidatedNodeType(item, type);
+		}
+
+		SqlNodeList list =
+			new SqlNodeList(sqlNodes, mr.getPatternDefList().getParserPosition());
+		inferUnknownTypes(unknownType, scope, list);
+		for (SqlNode node : list) {
+			validateExpr(node, scope);
+		}
+		mr.setOperand(SqlMatchRecognize.OPERAND_PATTERN_DEFINES, list);
+	}
+
+	/** Returns the alias of a "expr AS alias" expression. */
+	private static String alias(SqlNode item) {
+		assert item instanceof SqlCall;
+		assert item.getKind() == SqlKind.AS;
+		final SqlIdentifier identifier = ((SqlCall) item).operand(1);
+		return identifier.getSimple();
+	}
+
+	/** Checks that all pattern variables within a function are the same,
+	 * and canonizes expressions such as {@code PREV(B.price)} to
+	 * {@code LAST(B.price, 0)}. */
+	private SqlNode navigationInDefine(SqlNode node, String alpha) {
+		Set<String> prefix = node.accept(new PatternValidator(false));
+		Util.discard(prefix);
+		node = new NavigationExpander().go(node);
+		node = new NavigationReplacer(alpha).go(node);
+		return node;
+	}
+
+	public void validateAggregateParams(SqlCall aggCall, SqlNode filter,
+		SqlValidatorScope scope) {
+		// For "agg(expr)", expr cannot itself contain aggregate function
+		// invocations.  For example, "SUM(2 * MAX(x))" is illegal; when
+		// we see it, we'll report the error for the SUM (not the MAX).
+		// For more than one level of nesting, the error which results
+		// depends on the traversal order for validation.
+		//
+		// For a windowed aggregate "agg(expr)", expr can contain an aggregate
+		// function. For example,
+		//   SELECT AVG(2 * MAX(x)) OVER (PARTITION BY y)
+		//   FROM t
+		//   GROUP BY y
+		// is legal. Only one level of nesting is allowed since non-windowed
+		// aggregates cannot nest aggregates.
+
+		// Store nesting level of each aggregate. If an aggregate is found at an invalid
+		// nesting level, throw an assert.
+		final AggFinder a;
+		if (inWindow) {
+			a = overFinder;
+		} else {
+			a = aggOrOverFinder;
+		}
+
+		for (SqlNode param : aggCall.getOperandList()) {
+			if (a.findAgg(param) != null) {
+				throw newValidationError(aggCall, RESOURCE.nestedAggIllegal());
+			}
+		}
+		if (filter != null) {
+			if (a.findAgg(filter) != null) {
+				throw newValidationError(filter, RESOURCE.aggregateInFilterIllegal());
+			}
+		}
+	}
+
+	public void validateCall(
+		SqlCall call,
+		SqlValidatorScope scope) {
+		final SqlOperator operator = call.getOperator();
+		if ((call.operandCount() == 0)
+			&& (operator.getSyntax() == SqlSyntax.FUNCTION_ID)
+			&& !call.isExpanded()
+			&& !conformance.allowNiladicParentheses()) {
+			// For example, "LOCALTIME()" is illegal. (It should be
+			// "LOCALTIME", which would have been handled as a
+			// SqlIdentifier.)
+			throw handleUnresolvedFunction(call, (SqlFunction) operator,
+				ImmutableList.of(), null);
+		}
+
+		SqlValidatorScope operandScope = scope.getOperandScope(call);
+
+		if (operator instanceof SqlFunction
+			&& ((SqlFunction) operator).getFunctionType()
+			== SqlFunctionCategory.MATCH_RECOGNIZE
+			&& !(operandScope instanceof MatchRecognizeScope)) {
+			throw newValidationError(call,
+				Static.RESOURCE.functionMatchRecognizeOnly(call.toString()));
+		}
+		// Delegate validation to the operator.
+		operator.validateCall(call, this, scope, operandScope);
+	}
+
+	/**
+	 * Validates that a particular feature is enabled. By default, all features
+	 * are enabled; subclasses may override this method to be more
+	 * discriminating.
+	 *
+	 * @param feature feature being used, represented as a resource instance
+	 * @param context parser position context for error reporting, or null if
+	 */
+	protected void validateFeature(
+		Feature feature,
+		SqlParserPos context) {
+		// By default, do nothing except to verify that the resource
+		// represents a real feature definition.
+		assert feature.getProperties().get("FeatureDefinition") != null;
+	}
+
+	public SqlNode expand(SqlNode expr, SqlValidatorScope scope) {
+		final Expander expander = new Expander(this, scope);
+		SqlNode newExpr = expr.accept(expander);
+		if (expr != newExpr) {
+			setOriginal(newExpr, expr);
+		}
+		return newExpr;
+	}
+
+	public SqlNode expandGroupByOrHavingExpr(SqlNode expr,
+		SqlValidatorScope scope, SqlSelect select, boolean havingExpression) {
+		final Expander expander = new ExtendedExpander(this, scope, select, expr,
+			havingExpression);
+		SqlNode newExpr = expr.accept(expander);
+		if (expr != newExpr) {
+			setOriginal(newExpr, expr);
+		}
+		return newExpr;
+	}
+
+	public boolean isSystemField(RelDataTypeField field) {
+		return false;
+	}
+
+	public List<List<String>> getFieldOrigins(SqlNode sqlQuery) {
+		if (sqlQuery instanceof SqlExplain) {
+			return Collections.emptyList();
+		}
+		final RelDataType rowType = getValidatedNodeType(sqlQuery);
+		final int fieldCount = rowType.getFieldCount();
+		if (!sqlQuery.isA(SqlKind.QUERY)) {
+			return Collections.nCopies(fieldCount, null);
+		}
+		final List<List<String>> list = new ArrayList<>();
+		for (int i = 0; i < fieldCount; i++) {
+			list.add(getFieldOrigin(sqlQuery, i));
+		}
+		return ImmutableNullableList.copyOf(list);
+	}
+
+	private List<String> getFieldOrigin(SqlNode sqlQuery, int i) {
+		if (sqlQuery instanceof SqlSelect) {
+			SqlSelect sqlSelect = (SqlSelect) sqlQuery;
+			final SelectScope scope = getRawSelectScope(sqlSelect);
+			final List<SqlNode> selectList = scope.getExpandedSelectList();
+			final SqlNode selectItem = stripAs(selectList.get(i));
+			if (selectItem instanceof SqlIdentifier) {
+				final SqlQualified qualified =
+					scope.fullyQualify((SqlIdentifier) selectItem);
+				SqlValidatorNamespace namespace = qualified.namespace;
+				final SqlValidatorTable table = namespace.getTable();
+				if (table == null) {
+					return null;
+				}
+				final List<String> origin =
+					new ArrayList<>(table.getQualifiedName());
+				for (String name : qualified.suffix()) {
+					namespace = namespace.lookupChild(name);
+					if (namespace == null) {
+						return null;
+					}
+					origin.add(name);
+				}
+				return origin;
+			}
+			return null;
+		} else if (sqlQuery instanceof SqlOrderBy) {
+			return getFieldOrigin(((SqlOrderBy) sqlQuery).query, i);
+		} else {
+			return null;
+		}
+	}
+
+	public RelDataType getParameterRowType(SqlNode sqlQuery) {
+		// NOTE: We assume that bind variables occur in depth-first tree
+		// traversal in the same order that they occurred in the SQL text.
+		final List<RelDataType> types = new ArrayList<>();
+		// NOTE: but parameters on fetch/offset would be counted twice
+		// as they are counted in the SqlOrderBy call and the inner SqlSelect call
+		final Set<SqlNode> alreadyVisited = new HashSet<>();
+		sqlQuery.accept(
+			new SqlShuttle() {
+
+				@Override public SqlNode visit(SqlDynamicParam param) {
+					if (alreadyVisited.add(param)) {
+						RelDataType type = getValidatedNodeType(param);
+						types.add(type);
+					}
+					return param;
+				}
+			});
+		return typeFactory.createStructType(
+			types,
+			new AbstractList<String>() {
+				@Override public String get(int index) {
+					return "?" + index;
+				}
+
+				@Override public int size() {
+					return types.size();
+				}
+			});
+	}
+
+	public void validateColumnListParams(
+		SqlFunction function,
+		List<RelDataType> argTypes,
+		List<SqlNode> operands) {
+		throw new UnsupportedOperationException();
+	}
+
+	private static boolean isPhysicalNavigation(SqlKind kind) {
+		return kind == SqlKind.PREV || kind == SqlKind.NEXT;
+	}
+
+	private static boolean isLogicalNavigation(SqlKind kind) {
+		return kind == SqlKind.FIRST || kind == SqlKind.LAST;
+	}
+
+	private static boolean isAggregation(SqlKind kind) {
+		return kind == SqlKind.SUM || kind == SqlKind.SUM0
+			|| kind == SqlKind.AVG || kind == SqlKind.COUNT
+			|| kind == SqlKind.MAX || kind == SqlKind.MIN;
+	}
+
+	private static boolean isRunningOrFinal(SqlKind kind) {
+		return kind == SqlKind.RUNNING || kind == SqlKind.FINAL;
+	}
+
+	private static boolean isSingleVarRequired(SqlKind kind) {
+		return isPhysicalNavigation(kind)
+			|| isLogicalNavigation(kind)
+			|| isAggregation(kind);
+	}
+
+	//~ Inner Classes ----------------------------------------------------------
+
+	/**
+	 * Common base class for DML statement namespaces.
+	 */
+	public static class DmlNamespace extends IdentifierNamespace {
+		protected DmlNamespace(SqlValidatorImpl validator, SqlNode id,
+			SqlNode enclosingNode, SqlValidatorScope parentScope) {
+			super(validator, id, enclosingNode, parentScope);
+		}
+	}
+
+	/**
+	 * Namespace for an INSERT statement.
+	 */
+	private static class InsertNamespace extends DmlNamespace {
+		private final SqlInsert node;
+
+		InsertNamespace(SqlValidatorImpl validator, SqlInsert node,
+			SqlNode enclosingNode, SqlValidatorScope parentScope) {
+			super(validator, node.getTargetTable(), enclosingNode, parentScope);
+			this.node = Objects.requireNonNull(node);
+		}
+
+		public SqlInsert getNode() {
+			return node;
+		}
+	}
+
+	/**
+	 * Namespace for an UPDATE statement.
+	 */
+	private static class UpdateNamespace extends DmlNamespace {
+		private final SqlUpdate node;
+
+		UpdateNamespace(SqlValidatorImpl validator, SqlUpdate node,
+			SqlNode enclosingNode, SqlValidatorScope parentScope) {
+			super(validator, node.getTargetTable(), enclosingNode, parentScope);
+			this.node = Objects.requireNonNull(node);
+		}
+
+		public SqlUpdate getNode() {
+			return node;
+		}
+	}
+
+	/**
+	 * Namespace for a DELETE statement.
+	 */
+	private static class DeleteNamespace extends DmlNamespace {
+		private final SqlDelete node;
+
+		DeleteNamespace(SqlValidatorImpl validator, SqlDelete node,
+			SqlNode enclosingNode, SqlValidatorScope parentScope) {
+			super(validator, node.getTargetTable(), enclosingNode, parentScope);
+			this.node = Objects.requireNonNull(node);
+		}
+
+		public SqlDelete getNode() {
+			return node;
+		}
+	}
+
+	/**
+	 * Namespace for a MERGE statement.
+	 */
+	private static class MergeNamespace extends DmlNamespace {
+		private final SqlMerge node;
+
+		MergeNamespace(SqlValidatorImpl validator, SqlMerge node,
+			SqlNode enclosingNode, SqlValidatorScope parentScope) {
+			super(validator, node.getTargetTable(), enclosingNode, parentScope);
+			this.node = Objects.requireNonNull(node);
+		}
+
+		public SqlMerge getNode() {
+			return node;
+		}
+	}
+
+	/**
+	 * retrieve pattern variables defined
+	 */
+	private class PatternVarVisitor implements SqlVisitor<Void> {
+		private MatchRecognizeScope scope;
+		PatternVarVisitor(MatchRecognizeScope scope) {
+			this.scope = scope;
+		}
+
+		@Override public Void visit(SqlLiteral literal) {
+			return null;
+		}
+
+		@Override public Void visit(SqlCall call) {
+			for (int i = 0; i < call.getOperandList().size(); i++) {
+				call.getOperandList().get(i).accept(this);
+			}
+			return null;
+		}
+
+		@Override public Void visit(SqlNodeList nodeList) {
+			throw Util.needToImplement(nodeList);
+		}
+
+		@Override public Void visit(SqlIdentifier id) {
+			Preconditions.checkArgument(id.isSimple());
+			scope.addPatternVar(id.getSimple());
+			return null;
+		}
+
+		@Override public Void visit(SqlDataTypeSpec type) {
+			throw Util.needToImplement(type);
+		}
+
+		@Override public Void visit(SqlDynamicParam param) {
+			throw Util.needToImplement(param);
+		}
+
+		@Override public Void visit(SqlIntervalQualifier intervalQualifier) {
+			throw Util.needToImplement(intervalQualifier);
+		}
+	}
+
+	/**
+	 * Visitor which derives the type of a given {@link SqlNode}.
+	 *
+	 * <p>Each method must return the derived type. This visitor is basically a
+	 * single-use dispatcher; the visit is never recursive.
+	 */
+	private class DeriveTypeVisitor implements SqlVisitor<RelDataType> {
+		private final SqlValidatorScope scope;
+
+		DeriveTypeVisitor(SqlValidatorScope scope) {
+			this.scope = scope;
+		}
+
+		public RelDataType visit(SqlLiteral literal) {
+			return literal.createSqlType(typeFactory);
+		}
+
+		public RelDataType visit(SqlCall call) {
+			final SqlOperator operator = call.getOperator();
+			return operator.deriveType(SqlValidatorImpl.this, scope, call);
+		}
+
+		public RelDataType visit(SqlNodeList nodeList) {
+			// Operand is of a type that we can't derive a type for. If the
+			// operand is of a peculiar type, such as a SqlNodeList, then you
+			// should override the operator's validateCall() method so that it
+			// doesn't try to validate that operand as an expression.
+			throw Util.needToImplement(nodeList);
+		}
+
+		public RelDataType visit(SqlIdentifier id) {
+			// First check for builtin functions which don't have parentheses,
+			// like "LOCALTIME".
+			SqlCall call = SqlUtil.makeCall(opTab, id);
+			if (call != null) {
+				return call.getOperator().validateOperands(
+					SqlValidatorImpl.this,
+					scope,
+					call);
+			}
+
+			RelDataType type = null;
+			if (!(scope instanceof EmptyScope)) {
+				id = scope.fullyQualify(id).identifier;
+			}
+
+			// Resolve the longest prefix of id that we can
+			int i;
+			for (i = id.names.size() - 1; i > 0; i--) {
+				// REVIEW jvs 9-June-2005: The name resolution rules used
+				// here are supposed to match SQL:2003 Part 2 Section 6.6
+				// (identifier chain), but we don't currently have enough
+				// information to get everything right.  In particular,
+				// routine parameters are currently looked up via resolve;
+				// we could do a better job if they were looked up via
+				// resolveColumn.
+
+				final SqlNameMatcher nameMatcher = catalogReader.nameMatcher();
+				final SqlValidatorScope.ResolvedImpl resolved =
+					new SqlValidatorScope.ResolvedImpl();
+				scope.resolve(id.names.subList(0, i), nameMatcher, false, resolved);
+				if (resolved.count() == 1) {
+					// There's a namespace with the name we seek.
+					final SqlValidatorScope.Resolve resolve = resolved.only();
+					type = resolve.rowType();
+					for (SqlValidatorScope.Step p : Util.skip(resolve.path.steps())) {
+						type = type.getFieldList().get(p.i).getType();
+					}
+					break;
+				}
+			}
+
+			// Give precedence to namespace found, unless there
+			// are no more identifier components.
+			if (type == null || id.names.size() == 1) {
+				// See if there's a column with the name we seek in
+				// precisely one of the namespaces in this scope.
+				RelDataType colType = scope.resolveColumn(id.names.get(0), id);
+				if (colType != null) {
+					type = colType;
+				}
+				++i;
+			}
+
+			if (type == null) {
+				final SqlIdentifier last = id.getComponent(i - 1, i);
+				throw newValidationError(last,
+					RESOURCE.unknownIdentifier(last.toString()));
+			}
+
+			// Resolve rest of identifier
+			for (; i < id.names.size(); i++) {
+				String name = id.names.get(i);
+				final RelDataTypeField field;
+				if (name.equals("")) {
+					// The wildcard "*" is represented as an empty name. It never
+					// resolves to a field.
+					name = "*";
+					field = null;
+				} else {
+					final SqlNameMatcher nameMatcher = catalogReader.nameMatcher();
+					field = nameMatcher.field(type, name);
+				}
+				if (field == null) {
+					throw newValidationError(id.getComponent(i),
+						RESOURCE.unknownField(name));
+				}
+				type = field.getType();
+			}
+			type =
+				SqlTypeUtil.addCharsetAndCollation(
+					type,
+					getTypeFactory());
+			return type;
+		}
+
+		public RelDataType visit(SqlDataTypeSpec dataType) {
+			// Q. How can a data type have a type?
+			// A. When it appears in an expression. (Say as the 2nd arg to the
+			//    CAST operator.)
+			validateDataType(dataType);
+			return dataType.deriveType(SqlValidatorImpl.this);
+		}
+
+		public RelDataType visit(SqlDynamicParam param) {
+			return unknownType;
+		}
+
+		public RelDataType visit(SqlIntervalQualifier intervalQualifier) {
+			return typeFactory.createSqlIntervalType(intervalQualifier);
+		}
+	}
+
+	/**
+	 * Converts an expression into canonical form by fully-qualifying any
+	 * identifiers.
+	 */
+	private static class Expander extends SqlScopedShuttle {
+		protected final SqlValidatorImpl validator;
+
+		Expander(SqlValidatorImpl validator, SqlValidatorScope scope) {
+			super(scope);
+			this.validator = validator;
+		}
+
+		@Override public SqlNode visit(SqlIdentifier id) {
+			// First check for builtin functions which don't have
+			// parentheses, like "LOCALTIME".
+			SqlCall call =
+				SqlUtil.makeCall(
+					validator.getOperatorTable(),
+					id);
+			if (call != null) {
+				return call.accept(this);
+			}
+			final SqlIdentifier fqId = getScope().fullyQualify(id).identifier;
+			SqlNode expandedExpr = fqId;
+			// Convert a column ref into ITEM(*, 'col_name').
+			// select col_name from (select * from dynTable)
+			// SqlIdentifier "col_name" would be resolved to a dynamic star field in dynTable's rowType.
+			// Expand such SqlIdentifier to ITEM operator.
+			if (DynamicRecordType.isDynamicStarColName(Util.last(fqId.names))
+				&& !DynamicRecordType.isDynamicStarColName(Util.last(id.names))) {
+				SqlNode[] inputs = new SqlNode[2];
+				inputs[0] = fqId;
+				inputs[1] = SqlLiteral.createCharString(
+					Util.last(id.names),
+					id.getParserPosition());
+				SqlBasicCall item_call = new SqlBasicCall(
+					SqlStdOperatorTable.ITEM,
+					inputs,
+					id.getParserPosition());
+				expandedExpr = item_call;
+			}
+			validator.setOriginal(expandedExpr, id);
+			return expandedExpr;
+		}
+
+		@Override protected SqlNode visitScoped(SqlCall call) {
+			switch (call.getKind()) {
+				case SCALAR_QUERY:
+				case CURRENT_VALUE:
+				case NEXT_VALUE:
+				case WITH:
+					return call;
+			}
+			// Only visits arguments which are expressions. We don't want to
+			// qualify non-expressions such as 'x' in 'empno * 5 AS x'.
+			ArgHandler<SqlNode> argHandler =
+				new CallCopyingArgHandler(call, false);
+			call.getOperator().acceptCall(this, call, true, argHandler);
+			final SqlNode result = argHandler.result();
+			validator.setOriginal(result, call);
+			return result;
+		}
+	}
+
+	/**
+	 * Shuttle which walks over an expression in the ORDER BY clause, replacing
+	 * usages of aliases with the underlying expression.
+	 */
+	class OrderExpressionExpander extends SqlScopedShuttle {
+		private final List<String> aliasList;
+		private final SqlSelect select;
+		private final SqlNode root;
+
+		OrderExpressionExpander(SqlSelect select, SqlNode root) {
+			super(getOrderScope(select));
+			this.select = select;
+			this.root = root;
+			this.aliasList = getNamespace(select).getRowType().getFieldNames();
+		}
+
+		public SqlNode go() {
+			return root.accept(this);
+		}
+
+		public SqlNode visit(SqlLiteral literal) {
+			// Ordinal markers, e.g. 'select a, b from t order by 2'.
+			// Only recognize them if they are the whole expression,
+			// and if the dialect permits.
+			if (literal == root && getConformance().isSortByOrdinal()) {
+				switch (literal.getTypeName()) {
+					case DECIMAL:
+					case DOUBLE:
+						final int intValue = literal.intValue(false);
+						if (intValue >= 0) {
+							if (intValue < 1 || intValue > aliasList.size()) {
+								throw newValidationError(
+									literal, RESOURCE.orderByOrdinalOutOfRange());
+							}
+
+							// SQL ordinals are 1-based, but Sort's are 0-based
+							int ordinal = intValue - 1;
+							return nthSelectItem(ordinal, literal.getParserPosition());
+						}
+						break;
+				}
+			}
+
+			return super.visit(literal);
+		}
+
+		/**
+		 * Returns the <code>ordinal</code>th item in the select list.
+		 */
+		private SqlNode nthSelectItem(int ordinal, final SqlParserPos pos) {
+			// TODO: Don't expand the list every time. Maybe keep an expanded
+			// version of each expression -- select lists and identifiers -- in
+			// the validator.
+
+			SqlNodeList expandedSelectList =
+				expandStar(
+					select.getSelectList(),
+					select,
+					false);
+			SqlNode expr = expandedSelectList.get(ordinal);
+			expr = stripAs(expr);
+			if (expr instanceof SqlIdentifier) {
+				expr = getScope().fullyQualify((SqlIdentifier) expr).identifier;
+			}
+
+			// Create a copy of the expression with the position of the order
+			// item.
+			return expr.clone(pos);
+		}
+
+		public SqlNode visit(SqlIdentifier id) {
+			// Aliases, e.g. 'select a as x, b from t order by x'.
+			if (id.isSimple()
+				&& getConformance().isSortByAlias()) {
+				String alias = id.getSimple();
+				final SqlValidatorNamespace selectNs = getNamespace(select);
+				final RelDataType rowType =
+					selectNs.getRowTypeSansSystemColumns();
+				final SqlNameMatcher nameMatcher = catalogReader.nameMatcher();
+				RelDataTypeField field = nameMatcher.field(rowType, alias);
+				if (field != null) {
+					return nthSelectItem(
+						field.getIndex(),
+						id.getParserPosition());
+				}
+			}
+
+			// No match. Return identifier unchanged.
+			return getScope().fullyQualify(id).identifier;
+		}
+
+		protected SqlNode visitScoped(SqlCall call) {
+			// Don't attempt to expand sub-queries. We haven't implemented
+			// these yet.
+			if (call instanceof SqlSelect) {
+				return call;
+			}
+			return super.visitScoped(call);
+		}
+	}
+
+	/**
+	 * Shuttle which walks over an expression in the GROUP BY/HAVING clause, replacing
+	 * usages of aliases or ordinals with the underlying expression.
+	 */
+	static class ExtendedExpander extends Expander {
+		final SqlSelect select;
+		final SqlNode root;
+		final boolean havingExpr;
+
+		ExtendedExpander(SqlValidatorImpl validator, SqlValidatorScope scope,
+			SqlSelect select, SqlNode root, boolean havingExpr) {
+			super(validator, scope);
+			this.select = select;
+			this.root = root;
+			this.havingExpr = havingExpr;
+		}
+
+		@Override public SqlNode visit(SqlIdentifier id) {
+			if (id.isSimple()
+				&& (havingExpr
+					    ? validator.getConformance().isHavingAlias()
+					    : validator.getConformance().isGroupByAlias())) {
+				String name = id.getSimple();
+				SqlNode expr = null;
+				final SqlNameMatcher nameMatcher =
+					validator.catalogReader.nameMatcher();
+				int n = 0;
+				for (SqlNode s : select.getSelectList()) {
+					final String alias = SqlValidatorUtil.getAlias(s, -1);
+					if (alias != null && nameMatcher.matches(alias, name)) {
+						expr = s;
+						n++;
+					}
+				}
+				if (n == 0) {
+					return super.visit(id);
+				} else if (n > 1) {
+					// More than one column has this alias.
+					throw validator.newValidationError(id,
+						RESOURCE.columnAmbiguous(name));
+				}
+				if (havingExpr && validator.isAggregate(root)) {
+					return super.visit(id);
+				}
+				expr = stripAs(expr);
+				if (expr instanceof SqlIdentifier) {
+					expr = getScope().fullyQualify((SqlIdentifier) expr).identifier;
+				}
+				return expr;
+			}
+			return super.visit(id);
+		}
+
+		public SqlNode visit(SqlLiteral literal) {
+			if (havingExpr || !validator.getConformance().isGroupByOrdinal()) {
+				return super.visit(literal);
+			}
+			boolean isOrdinalLiteral = literal == root;
+			switch (root.getKind()) {
+				case GROUPING_SETS:
+				case ROLLUP:
+				case CUBE:
+					if (root instanceof SqlBasicCall) {
+						List<SqlNode> operandList = ((SqlBasicCall) root).getOperandList();
+						for (SqlNode node : operandList) {
+							if (node.equals(literal)) {
+								isOrdinalLiteral = true;
+								break;
+							}
+						}
+					}
+					break;
+			}
+			if (isOrdinalLiteral) {
+				switch (literal.getTypeName()) {
+					case DECIMAL:
+					case DOUBLE:
+						final int intValue = literal.intValue(false);
+						if (intValue >= 0) {
+							if (intValue < 1 || intValue > select.getSelectList().size()) {
+								throw validator.newValidationError(literal,
+									RESOURCE.orderByOrdinalOutOfRange());
+							}
+
+							// SQL ordinals are 1-based, but Sort's are 0-based
+							int ordinal = intValue - 1;
+							return SqlUtil.stripAs(select.getSelectList().get(ordinal));
+						}
+						break;
+				}
+			}
+
+			return super.visit(literal);
+		}
+	}
+
+	/** Information about an identifier in a particular scope. */
+	protected static class IdInfo {
+		public final SqlValidatorScope scope;
+		public final SqlIdentifier id;
+
+		public IdInfo(SqlValidatorScope scope, SqlIdentifier id) {
+			this.scope = scope;
+			this.id = id;
+		}
+	}
+
+	/**
+	 * Utility object used to maintain information about the parameters in a
+	 * function call.
+	 */
+	protected static class FunctionParamInfo {
+		/**
+		 * Maps a cursor (based on its position relative to other cursor
+		 * parameters within a function call) to the SELECT associated with the
+		 * cursor.
+		 */
+		public final Map<Integer, SqlSelect> cursorPosToSelectMap;
+
+		/**
+		 * Maps a column list parameter to the parent cursor parameter it
+		 * references. The parameters are id'd by their names.
+		 */
+		public final Map<String, String> columnListParamToParentCursorMap;
+
+		public FunctionParamInfo() {
+			cursorPosToSelectMap = new HashMap<>();
+			columnListParamToParentCursorMap = new HashMap<>();
+		}
+	}
+
+	/**
+	 * Modify the nodes in navigation function
+	 * such as FIRST, LAST, PREV AND NEXT.
+	 */
+	private static class NavigationModifier extends SqlShuttle {
+		public SqlNode go(SqlNode node) {
+			return node.accept(this);
+		}
+	}
+
+	/**
+	 * Shuttle that expands navigation expressions in a MATCH_RECOGNIZE clause.
+	 *
+	 * <p>Examples:
+	 *
+	 * <ul>
+	 *   <li>{@code PREV(A.price + A.amount)} &rarr;
+	 *   {@code PREV(A.price) + PREV(A.amount)}
+	 *
+	 *   <li>{@code FIRST(A.price * 2)} &rarr; {@code FIRST(A.PRICE) * 2}
+	 * </ul>
+	 */
+	private static class NavigationExpander extends NavigationModifier {
+		final SqlOperator op;
+		final SqlNode offset;
+
+		NavigationExpander() {
+			this(null, null);
+		}
+
+		NavigationExpander(SqlOperator operator, SqlNode offset) {
+			this.offset = offset;
+			this.op = operator;
+		}
+
+		@Override public SqlNode visit(SqlCall call) {
+			SqlKind kind = call.getKind();
+			List<SqlNode> operands = call.getOperandList();
+			List<SqlNode> newOperands = new ArrayList<>();
+
+			// This code is a workaround for CALCITE-2707
+			if (call.getFunctionQuantifier() != null
+				&& call.getFunctionQuantifier().getValue() == SqlSelectKeyword.DISTINCT) {
+				final SqlParserPos pos = call.getParserPosition();
+				throw SqlUtil.newContextException(pos, Static.RESOURCE.functionQuantifierNotAllowed(call.toString()));
+			}
+			// This code is a workaround for CALCITE-2707
+
+			if (isLogicalNavigation(kind) || isPhysicalNavigation(kind)) {
+				SqlNode inner = operands.get(0);
+				SqlNode offset = operands.get(1);
+
+				// merge two straight prev/next, update offset
+				if (isPhysicalNavigation(kind)) {
+					SqlKind innerKind = inner.getKind();
+					if (isPhysicalNavigation(innerKind)) {
+						List<SqlNode> innerOperands = ((SqlCall) inner).getOperandList();
+						SqlNode innerOffset = innerOperands.get(1);
+						SqlOperator newOperator = innerKind == kind
+							? SqlStdOperatorTable.PLUS : SqlStdOperatorTable.MINUS;
+						offset = newOperator.createCall(SqlParserPos.ZERO,
+							offset, innerOffset);
+						inner = call.getOperator().createCall(SqlParserPos.ZERO,
+							innerOperands.get(0), offset);
+					}
+				}
+				SqlNode newInnerNode =
+					inner.accept(new NavigationExpander(call.getOperator(), offset));
+				if (op != null) {
+					newInnerNode = op.createCall(SqlParserPos.ZERO, newInnerNode,
+						this.offset);
+				}
+				return newInnerNode;
+			}
+
+			if (operands.size() > 0) {
+				for (SqlNode node : operands) {
+					if (node != null) {
+						SqlNode newNode = node.accept(new NavigationExpander());
+						if (op != null) {
+							newNode = op.createCall(SqlParserPos.ZERO, newNode, offset);
+						}
+						newOperands.add(newNode);
+					} else {
+						newOperands.add(null);
+					}
+				}
+				return call.getOperator().createCall(SqlParserPos.ZERO, newOperands);
+			} else {
+				if (op == null) {
+					return call;
+				} else {
+					return op.createCall(SqlParserPos.ZERO, call, offset);
+				}
+			}
+		}
+
+		@Override public SqlNode visit(SqlIdentifier id) {
+			if (op == null) {
+				return id;
+			} else {
+				return op.createCall(SqlParserPos.ZERO, id, offset);
+			}
+		}
+	}
+
+	/**
+	 * Shuttle that replaces {@code A as A.price > PREV(B.price)} with
+	 * {@code PREV(A.price, 0) > LAST(B.price, 0)}.
+	 *
+	 * <p>Replacing {@code A.price} with {@code PREV(A.price, 0)} makes the
+	 * implementation of
+	 * {@link RexVisitor#visitPatternFieldRef(RexPatternFieldRef)} more unified.
+	 * Otherwise, it's difficult to implement this method. If it returns the
+	 * specified field, then the navigation such as {@code PREV(A.price, 1)}
+	 * becomes impossible; if not, then comparisons such as
+	 * {@code A.price > PREV(A.price, 1)} become meaningless.
+	 */
+	private static class NavigationReplacer extends NavigationModifier {
+		private final String alpha;
+
+		NavigationReplacer(String alpha) {
+			this.alpha = alpha;
+		}
+
+		@Override public SqlNode visit(SqlCall call) {
+			SqlKind kind = call.getKind();
+			if (isLogicalNavigation(kind)
+				|| isAggregation(kind)
+				|| isRunningOrFinal(kind)) {
+				return call;
+			}
+
+			switch (kind) {
+				case PREV:
+					final List<SqlNode> operands = call.getOperandList();
+					if (operands.get(0) instanceof SqlIdentifier) {
+						String name = ((SqlIdentifier) operands.get(0)).names.get(0);
+						return name.equals(alpha) ? call
+							: SqlStdOperatorTable.LAST.createCall(SqlParserPos.ZERO, operands);
+					}
+			}
+			return super.visit(call);
+		}
+
+		@Override public SqlNode visit(SqlIdentifier id) {
+			if (id.isSimple()) {
+				return id;
+			}
+			SqlOperator operator = id.names.get(0).equals(alpha)
+				? SqlStdOperatorTable.PREV : SqlStdOperatorTable.LAST;
+
+			return operator.createCall(SqlParserPos.ZERO, id,
+				SqlLiteral.createExactNumeric("0", SqlParserPos.ZERO));
+		}
+	}
+
+	/**
+	 * Within one navigation function, the pattern var should be same
+	 */
+	private class PatternValidator extends SqlBasicVisitor<Set<String>> {
+		private final boolean isMeasure;
+		int firstLastCount;
+		int prevNextCount;
+		int aggregateCount;
+
+		PatternValidator(boolean isMeasure) {
+			this(isMeasure, 0, 0, 0);
+		}
+
+		PatternValidator(boolean isMeasure, int firstLastCount, int prevNextCount,
+			int aggregateCount) {
+			this.isMeasure = isMeasure;
+			this.firstLastCount = firstLastCount;
+			this.prevNextCount = prevNextCount;
+			this.aggregateCount = aggregateCount;
+		}
+
+		@Override public Set<String> visit(SqlCall call) {
+			boolean isSingle = false;
+			Set<String> vars = new HashSet<>();
+			SqlKind kind = call.getKind();
+			List<SqlNode> operands = call.getOperandList();
+
+			if (isSingleVarRequired(kind)) {
+				isSingle = true;
+				if (isPhysicalNavigation(kind)) {
+					if (isMeasure) {
+						throw newValidationError(call,
+							Static.RESOURCE.patternPrevFunctionInMeasure(call.toString()));
+					}
+					if (firstLastCount != 0) {
+						throw newValidationError(call,
+							Static.RESOURCE.patternPrevFunctionOrder(call.toString()));
+					}
+					prevNextCount++;
+				} else if (isLogicalNavigation(kind)) {
+					if (firstLastCount != 0) {
+						throw newValidationError(call,
+							Static.RESOURCE.patternPrevFunctionOrder(call.toString()));
+					}
+					firstLastCount++;
+				} else if (isAggregation(kind)) {
+					// cannot apply aggregation in PREV/NEXT, FIRST/LAST
+					if (firstLastCount != 0 || prevNextCount != 0) {
+						throw newValidationError(call,
+							Static.RESOURCE.patternAggregationInNavigation(call.toString()));
+					}
+					if (kind == SqlKind.COUNT && call.getOperandList().size() > 1) {
+						throw newValidationError(call,
+							Static.RESOURCE.patternCountFunctionArg());
+					}
+					aggregateCount++;
+				}
+			}
+
+			if (isRunningOrFinal(kind) && !isMeasure) {
+				throw newValidationError(call,
+					Static.RESOURCE.patternRunningFunctionInDefine(call.toString()));
+			}
+
+			for (SqlNode node : operands) {
+				if (node != null) {
+					vars.addAll(
+						node.accept(
+							new PatternValidator(isMeasure, firstLastCount, prevNextCount,
+								aggregateCount)));
+				}
+			}
+
+			if (isSingle) {
+				switch (kind) {
+					case COUNT:
+						if (vars.size() > 1) {
+							throw newValidationError(call,
+								Static.RESOURCE.patternCountFunctionArg());
+						}
+						break;
+					default:
+						if (operands.size() == 0
+							|| !(operands.get(0) instanceof SqlCall)
+							|| ((SqlCall) operands.get(0)).getOperator() != SqlStdOperatorTable.CLASSIFIER) {
+							if (vars.isEmpty()) {
+								throw newValidationError(call,
+									Static.RESOURCE.patternFunctionNullCheck(call.toString()));
+							}
+							if (vars.size() != 1) {
+								throw newValidationError(call,
+									Static.RESOURCE.patternFunctionVariableCheck(call.toString()));
+							}
+						}
+						break;
+				}
+			}
+			return vars;
+		}
+
+		@Override public Set<String> visit(SqlIdentifier identifier) {
+			boolean check = prevNextCount > 0 || firstLastCount > 0 || aggregateCount > 0;
+			Set<String> vars = new HashSet<>();
+			if (identifier.names.size() > 1 && check) {
+				vars.add(identifier.names.get(0));
+			}
+			return vars;
+		}
+
+		@Override public Set<String> visit(SqlLiteral literal) {
+			return ImmutableSet.of();
+		}
+
+		@Override public Set<String> visit(SqlIntervalQualifier qualifier) {
+			return ImmutableSet.of();
+		}
+
+		@Override public Set<String> visit(SqlDataTypeSpec type) {
+			return ImmutableSet.of();
+		}
+
+		@Override public Set<String> visit(SqlDynamicParam param) {
+			return ImmutableSet.of();
+		}
+	}
+
+	/** Permutation of fields in NATURAL JOIN or USING. */
+	private class Permute {
+		final List<ImmutableIntList> sources;
+		final RelDataType rowType;
+		final boolean trivial;
+
+		Permute(SqlNode from, int offset) {
+			switch (from.getKind()) {
+				case JOIN:
+					final SqlJoin join = (SqlJoin) from;
+					final Permute left = new Permute(join.getLeft(), offset);
+					final int fieldCount =
+						getValidatedNodeType(join.getLeft()).getFieldList().size();
+					final Permute right =
+						new Permute(join.getRight(), offset + fieldCount);
+					final List<String> names = usingNames(join);
+					final List<ImmutableIntList> sources = new ArrayList<>();
+					final Set<ImmutableIntList> sourceSet = new HashSet<>();
+					final RelDataTypeFactory.Builder b = typeFactory.builder();
+					if (names != null) {
+						for (String name : names) {
+							final RelDataTypeField f = left.field(name);
+							final ImmutableIntList source = left.sources.get(f.getIndex());
+							sourceSet.add(source);
+							final RelDataTypeField f2 = right.field(name);
+							final ImmutableIntList source2 = right.sources.get(f2.getIndex());
+							sourceSet.add(source2);
+							sources.add(source.appendAll(source2));
+							final boolean nullable =
+								(f.getType().isNullable()
+									 || join.getJoinType().generatesNullsOnLeft())
+									&& (f2.getType().isNullable()
+										    || join.getJoinType().generatesNullsOnRight());
+							b.add(f).nullable(nullable);
+						}
+					}
+					for (RelDataTypeField f : left.rowType.getFieldList()) {
+						final ImmutableIntList source = left.sources.get(f.getIndex());
+						if (sourceSet.add(source)) {
+							sources.add(source);
+							b.add(f);
+						}
+					}
+					for (RelDataTypeField f : right.rowType.getFieldList()) {
+						final ImmutableIntList source = right.sources.get(f.getIndex());
+						if (sourceSet.add(source)) {
+							sources.add(source);
+							b.add(f);
+						}
+					}
+					rowType = b.build();
+					this.sources = ImmutableList.copyOf(sources);
+					this.trivial = left.trivial
+						&& right.trivial
+						&& (names == null || names.isEmpty());
+					break;
+
+				default:
+					rowType = getValidatedNodeType(from);
+					this.sources = Functions.generate(rowType.getFieldCount(),
+						i -> ImmutableIntList.of(offset + i));
+					this.trivial = true;
+			}
+		}
+
+		private RelDataTypeField field(String name) {
+			return catalogReader.nameMatcher().field(rowType, name);
+		}
+
+		/** Returns the set of field names in the join condition specified by USING
+		 * or implicitly by NATURAL, de-duplicated and in order. */
+		private List<String> usingNames(SqlJoin join) {
+			switch (join.getConditionType()) {
+				case USING:
+					final ImmutableList.Builder<String> list = ImmutableList.builder();
+					final Set<String> names = catalogReader.nameMatcher().createSet();
+					for (SqlNode node : (SqlNodeList) join.getCondition()) {
+						final String name = ((SqlIdentifier) node).getSimple();
+						if (names.add(name)) {
+							list.add(name);
+						}
+					}
+					return list.build();
+				case NONE:
+					if (join.isNatural()) {
+						final RelDataType t0 = getValidatedNodeType(join.getLeft());
+						final RelDataType t1 = getValidatedNodeType(join.getRight());
+						return SqlValidatorUtil.deriveNaturalJoinColumnList(
+							catalogReader.nameMatcher(), t0, t1);
+					}
+			}
+			return null;
+		}
+
+		/** Moves fields according to the permutation. */
+		public void permute(List<SqlNode> selectItems,
+			List<Map.Entry<String, RelDataType>> fields) {
+			if (trivial) {
+				return;
+			}
+
+			final List<SqlNode> oldSelectItems = ImmutableList.copyOf(selectItems);
+			selectItems.clear();
+			final List<Map.Entry<String, RelDataType>> oldFields =
+				ImmutableList.copyOf(fields);
+			fields.clear();
+			for (ImmutableIntList source : sources) {
+				final int p0 = source.get(0);
+				Map.Entry<String, RelDataType> field = oldFields.get(p0);
+				final String name = field.getKey();
+				RelDataType type = field.getValue();
+				SqlNode selectItem = oldSelectItems.get(p0);
+				for (int p1 : Util.skip(source)) {
+					final Map.Entry<String, RelDataType> field1 = oldFields.get(p1);
+					final SqlNode selectItem1 = oldSelectItems.get(p1);
+					final RelDataType type1 = field1.getValue();
+					// output is nullable only if both inputs are
+					final boolean nullable = type.isNullable() && type1.isNullable();
+					final RelDataType type2 =
+						SqlTypeUtil.leastRestrictiveForComparison(typeFactory, type,
+							type1);
+					selectItem =
+						SqlStdOperatorTable.AS.createCall(SqlParserPos.ZERO,
+							SqlStdOperatorTable.COALESCE.createCall(SqlParserPos.ZERO,
+								maybeCast(selectItem, type, type2),
+								maybeCast(selectItem1, type1, type2)),
+							new SqlIdentifier(name, SqlParserPos.ZERO));
+					type = typeFactory.createTypeWithNullability(type2, nullable);
+				}
+				fields.add(Pair.of(name, type));
+				selectItems.add(selectItem);
+			}
+		}
+	}
+
+	//~ Enums ------------------------------------------------------------------
+
+	/**
+	 * Validation status.
+	 */
+	public enum Status {
+		/**
+		 * Validation has not started for this scope.
+		 */
+		UNVALIDATED,
+
+		/**
+		 * Validation is in progress for this scope.
+		 */
+		IN_PROGRESS,
+
+		/**
+		 * Validation has completed (perhaps unsuccessfully).
+		 */
+		VALID
+	}
+
+}
+
+// End SqlValidatorImpl.java
diff --git a/flink-libraries/flink-table/src/test/scala/org/apache/flink/table/match/MatchRecognizeValidationTest.scala b/flink-libraries/flink-table/src/test/scala/org/apache/flink/table/match/MatchRecognizeValidationTest.scala
index 2890179..b77a60e 100644
--- a/flink-libraries/flink-table/src/test/scala/org/apache/flink/table/match/MatchRecognizeValidationTest.scala
+++ b/flink-libraries/flink-table/src/test/scala/org/apache/flink/table/match/MatchRecognizeValidationTest.scala
@@ -247,4 +247,25 @@ class MatchRecognizeValidationTest extends TableTestBase {
 
     streamUtils.tableEnv.sqlQuery(sqlQuery).toAppendStream[Row]
   }
+
+  @Test
+  def testDistinctAggregationsNotSupported(): Unit = {
+    thrown.expect(classOf[ValidationException])
+
+    val sqlQuery =
+      s"""
+         |SELECT *
+         |FROM Ticker
+         |MATCH_RECOGNIZE (
+         |  ORDER BY proctime
+         |  MEASURES
+         |    COUNT(DISTINCT A.price) AS price
+         |  PATTERN (A B)
+         |  DEFINE
+         |    A AS A.symbol = 'a'
+         |) AS T
+         |""".stripMargin
+
+    streamUtils.tableEnv.sqlQuery(sqlQuery).toAppendStream[Row]
+  }
 }
diff --git a/flink-libraries/flink-table/src/test/scala/org/apache/flink/table/runtime/stream/sql/MatchRecognizeITCase.scala b/flink-libraries/flink-table/src/test/scala/org/apache/flink/table/runtime/stream/sql/MatchRecognizeITCase.scala
index ffd1c2b..56087be 100644
--- a/flink-libraries/flink-table/src/test/scala/org/apache/flink/table/runtime/stream/sql/MatchRecognizeITCase.scala
+++ b/flink-libraries/flink-table/src/test/scala/org/apache/flink/table/runtime/stream/sql/MatchRecognizeITCase.scala
@@ -510,7 +510,7 @@ class MatchRecognizeITCase extends StreamingWithStateTestBase {
          |  MEASURES
          |    FIRST(id) as startId,
          |    SUM(A.price) AS sumA,
-         |    COUNT(DISTINCT D.price) AS countD,
+         |    COUNT(D.price) AS countD,
          |    SUM(D.price) as sumD,
          |    weightedAvg(price, weight) as wAvg,
          |    AVG(B.price) AS avgB,