[GitHub] [druid] github-code-scanning[bot] commented on a diff in pull request #14232: Decouple logical planning and native query generation in SQL planning

["github-code-scanning[bot] (via GitHub)" <gi...@apache.org>]

github-code-scanning[bot] commented on code in PR #14232:
URL: https://github.com/apache/druid/pull/14232#discussion_r1188216381


##########
sql/src/main/java/org/apache/calcite/plan/volcano/DruidVolcanoCost.java:
##########
@@ -0,0 +1,288 @@
+/*
+ * 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.
+ */
+
+//CHECKSTYLE.OFF: PackageName - Must be in Calcite
+
+package org.apache.calcite.plan.volcano;
+
+import org.apache.calcite.plan.RelOptCost;
+import org.apache.calcite.plan.RelOptCostFactory;
+import org.apache.calcite.plan.RelOptUtil;
+
+import java.util.Objects;
+
+/**
+ * Druid's extension to {@link VolcanoCost}. The difference between the two is in
+ * comparing two costs. Druid's cost model gives most weightage to rowCount, then to cpuCost and then lastly ioCost.
+ */
+public class DruidVolcanoCost implements RelOptCost
+{
+
+  static final DruidVolcanoCost INFINITY = new DruidVolcanoCost(
+      Double.POSITIVE_INFINITY,
+      Double.POSITIVE_INFINITY,
+      Double.POSITIVE_INFINITY
+  )
+  {
+    @Override
+    public String toString()
+    {
+      return "{inf}";
+    }
+  };
+
+  //CHECKSTYLE.OFF: Regexp
+  static final DruidVolcanoCost HUGE = new DruidVolcanoCost(Double.MAX_VALUE, Double.MAX_VALUE, Double.MAX_VALUE) {
+    @Override
+    public String toString()
+    {
+      return "{huge}";
+    }
+  };
+  //CHECKSTYLE.ON: Regexp
+
+  static final DruidVolcanoCost ZERO =
+      new DruidVolcanoCost(0.0, 0.0, 0.0)
+      {
+        @Override
+        public String toString()
+        {
+          return "{0}";
+        }
+      };
+
+  static final DruidVolcanoCost TINY =
+      new DruidVolcanoCost(1.0, 1.0, 0.0)
+      {
+        @Override
+        public String toString()
+        {
+          return "{tiny}";
+        }
+      };
+
+  public static final RelOptCostFactory FACTORY = new Factory();
+
+  final double cpu;
+  final double io;
+  final double rowCount;
+
+  DruidVolcanoCost(double rowCount, double cpu, double io)
+  {
+    this.rowCount = rowCount;
+    this.cpu = cpu;
+    this.io = io;
+  }
+
+  @Override
+  public double getCpu()
+  {
+    return cpu;
+  }
+
+  @Override
+  public boolean isInfinite()
+  {
+    return (this == INFINITY)
+           || (this.rowCount == Double.POSITIVE_INFINITY)
+           || (this.cpu == Double.POSITIVE_INFINITY)
+           || (this.io == Double.POSITIVE_INFINITY);
+  }
+
+  @Override
+  public double getIo()
+  {
+    return io;
+  }
+
+  @Override
+  public boolean isLe(RelOptCost other)
+  {
+    DruidVolcanoCost that = (DruidVolcanoCost) other;
+    return (this == that)
+           || ((this.rowCount < that.rowCount)
+               || (this.rowCount == that.rowCount && this.cpu < that.cpu)
+               || (this.rowCount == that.rowCount && this.cpu == that.cpu && this.io <= that.io));
+  }
+
+  @Override
+  public boolean isLt(RelOptCost other)
+  {
+    return isLe(other) && !equals(other);
+  }
+
+  @Override
+  public double getRows()
+  {
+    return rowCount;
+  }
+
+  @Override
+  public int hashCode()
+  {
+    return Objects.hash(rowCount, cpu, io);
+  }
+
+  @Override
+  public boolean equals(RelOptCost other)
+  {
+    return this == other
+           || other instanceof DruidVolcanoCost
+              && (this.rowCount == ((DruidVolcanoCost) other).rowCount)
+              && (this.cpu == ((DruidVolcanoCost) other).cpu)
+              && (this.io == ((DruidVolcanoCost) other).io);
+  }
+
+  @Override
+  public boolean equals(Object obj)

Review Comment:
   ## Confusing overloading of methods
   
   Method DruidVolcanoCost.equals(..) could be confused with overloaded method [equals](1), since dispatch depends on static types.
   
   [Show more details](https://github.com/apache/druid/security/code-scanning/4927)



##########
sql/src/main/java/org/apache/druid/sql/calcite/planner/DruidQueryGenerator.java:
##########
@@ -0,0 +1,336 @@
+/*
+ * 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.druid.sql.calcite.planner;
+
+import com.google.common.collect.ImmutableList;
+import org.apache.calcite.plan.RelOptTable;
+import org.apache.calcite.rel.RelNode;
+import org.apache.calcite.rel.RelShuttleImpl;
+import org.apache.calcite.rel.core.Aggregate;
+import org.apache.calcite.rel.core.Filter;
+import org.apache.calcite.rel.core.Project;
+import org.apache.calcite.rel.core.Sort;
+import org.apache.calcite.rel.core.TableFunctionScan;
+import org.apache.calcite.rel.core.TableScan;
+import org.apache.calcite.rel.logical.LogicalAggregate;
+import org.apache.calcite.rel.logical.LogicalCorrelate;
+import org.apache.calcite.rel.logical.LogicalExchange;
+import org.apache.calcite.rel.logical.LogicalFilter;
+import org.apache.calcite.rel.logical.LogicalIntersect;
+import org.apache.calcite.rel.logical.LogicalJoin;
+import org.apache.calcite.rel.logical.LogicalMatch;
+import org.apache.calcite.rel.logical.LogicalMinus;
+import org.apache.calcite.rel.logical.LogicalProject;
+import org.apache.calcite.rel.logical.LogicalSort;
+import org.apache.calcite.rel.logical.LogicalUnion;
+import org.apache.calcite.rel.logical.LogicalValues;
+import org.apache.calcite.rex.RexLiteral;
+import org.apache.druid.java.util.common.ISE;
+import org.apache.druid.query.InlineDataSource;
+import org.apache.druid.segment.column.RowSignature;
+import org.apache.druid.sql.calcite.rel.PartialDruidQuery;
+import org.apache.druid.sql.calcite.rel.logical.DruidTableScan;
+import org.apache.druid.sql.calcite.rule.DruidLogicalValuesRule;
+import org.apache.druid.sql.calcite.table.DruidTable;
+import org.apache.druid.sql.calcite.table.InlineTable;
+import org.apache.druid.sql.calcite.table.RowSignatures;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Collectors;
+
+
+/**
+ * Converts a DAG of {@link org.apache.druid.sql.calcite.rel.logical.DruidLogicalNode} convention to a native
+ * Druid query for execution. The convertion is done via a {@link org.apache.calcite.rel.RelShuttle} visitor
+ * implementation.
+ */
+public class DruidQueryGenerator extends RelShuttleImpl
+{
+  private final List<PartialDruidQuery> queryList = new ArrayList<>();
+  private final List<DruidTable> queryTables = new ArrayList<>();
+  private final PlannerContext plannerContext;
+  private PartialDruidQuery partialDruidQuery;
+  private PartialDruidQuery.Stage currentStage = null;
+  private DruidTable currentTable = null;
+  private boolean isRoot = true;
+
+  public DruidQueryGenerator(PlannerContext plannerContext)
+  {
+    this.plannerContext = plannerContext;
+  }
+
+  @Override
+  public RelNode visit(TableScan scan)
+  {
+    if (!(scan instanceof DruidTableScan)) {
+      throw new ISE("Planning hasn't converted logical table scan to druid convention");
+    }
+    DruidTableScan druidTableScan = (DruidTableScan) scan;
+    isRoot = false;
+    RelNode result = super.visit(scan);
+    partialDruidQuery = PartialDruidQuery.create(scan);
+    currentStage = PartialDruidQuery.Stage.SCAN;
+    final RelOptTable table = scan.getTable();
+    final DruidTable druidTable = table.unwrap(DruidTable.class);
+    if (druidTable != null) {
+      currentTable = druidTable;
+    }
+    if (druidTableScan.getProject() != null) {
+      partialDruidQuery = partialDruidQuery.withSelectProject(druidTableScan.getProject());
+      currentStage = PartialDruidQuery.Stage.SELECT_PROJECT;
+    }
+    return result;
+  }
+
+  @Override
+  public RelNode visit(TableFunctionScan scan)
+  {
+    return null;
+  }
+
+  @Override
+  public RelNode visit(LogicalValues values)
+  {
+    isRoot = false;
+    RelNode result = super.visit(values);
+    final List<ImmutableList<RexLiteral>> tuples = values.getTuples();
+    final List<Object[]> objectTuples = tuples
+        .stream()
+        .map(tuple -> tuple
+            .stream()
+            .map(v -> DruidLogicalValuesRule.getValueFromLiteral(v, plannerContext))
+            .collect(Collectors.toList())
+            .toArray(new Object[0])
+        )
+        .collect(Collectors.toList());
+    RowSignature rowSignature = RowSignatures.fromRelDataType(
+        values.getRowType().getFieldNames(),
+        values.getRowType()
+    );
+    currentTable = new InlineTable(InlineDataSource.fromIterable(objectTuples, rowSignature));
+    if (currentStage == null) {
+      partialDruidQuery = PartialDruidQuery.create(values);
+      currentStage = PartialDruidQuery.Stage.SCAN;
+    } else {
+      throw new ISE("Values node found at non leaf node in the plan");
+    }
+    return result;
+  }
+
+  @Override
+  public RelNode visit(LogicalFilter filter)
+  {
+    return visitFilter(filter);
+  }
+
+  public RelNode visitFilter(Filter filter)
+  {
+    isRoot = false;
+    RelNode result = super.visit(filter);
+    if (currentStage == PartialDruidQuery.Stage.AGGREGATE) {
+      partialDruidQuery = partialDruidQuery.withHavingFilter(filter);
+      currentStage = PartialDruidQuery.Stage.HAVING_FILTER;
+    } else if (currentStage == PartialDruidQuery.Stage.SCAN) {
+      partialDruidQuery = partialDruidQuery.withWhereFilter(filter);
+      currentStage = PartialDruidQuery.Stage.WHERE_FILTER;
+    } else if (currentStage == PartialDruidQuery.Stage.SELECT_PROJECT) {
+      PartialDruidQuery old = partialDruidQuery;
+      partialDruidQuery = PartialDruidQuery.create(old.getScan());
+      partialDruidQuery = partialDruidQuery.withWhereFilter(filter);
+      partialDruidQuery = partialDruidQuery.withSelectProject(old.getSelectProject());
+      currentStage = PartialDruidQuery.Stage.SELECT_PROJECT;
+    } else {
+      queryList.add(partialDruidQuery);
+      queryTables.add(currentTable);
+      partialDruidQuery = PartialDruidQuery.createOuterQuery(partialDruidQuery).withWhereFilter(filter);
+      currentStage = PartialDruidQuery.Stage.WHERE_FILTER;
+    }
+    return result;
+  }
+
+  @Override
+  public RelNode visit(LogicalProject project)
+  {
+    return visitProject(project);
+  }
+
+  @Override
+  public RelNode visit(LogicalJoin join)
+  {
+    throw new UnsupportedOperationException("Found join");
+  }
+
+  @Override
+  public RelNode visit(LogicalCorrelate correlate)
+  {
+    return null;
+  }
+
+  @Override
+  public RelNode visit(LogicalUnion union)
+  {
+    throw new UnsupportedOperationException("Found union");
+  }
+
+  @Override
+  public RelNode visit(LogicalIntersect intersect)
+  {
+    return null;
+  }
+
+  @Override
+  public RelNode visit(LogicalMinus minus)
+  {
+    return null;
+  }
+
+  @Override
+  public RelNode visit(LogicalAggregate aggregate)
+  {
+    isRoot = false;
+    RelNode result = super.visit(aggregate);
+    if (PartialDruidQuery.Stage.AGGREGATE.canFollow(currentStage)) {
+      partialDruidQuery = partialDruidQuery.withAggregate(aggregate);
+    } else {
+      queryList.add(partialDruidQuery);
+      queryTables.add(currentTable);
+      partialDruidQuery = PartialDruidQuery.createOuterQuery(partialDruidQuery).withAggregate(aggregate);
+    }
+    currentStage = PartialDruidQuery.Stage.AGGREGATE;
+    return result;
+  }
+
+  @Override
+  public RelNode visit(LogicalMatch match)
+  {
+    return null;
+  }
+
+  @Override
+  public RelNode visit(LogicalSort sort)
+  {
+    return visitSort(sort);
+  }
+
+  @Override
+  public RelNode visit(LogicalExchange exchange)
+  {
+    return null;
+  }
+
+  private RelNode visitProject(Project project)
+  {
+    boolean rootForReal = isRoot;
+    isRoot = false;
+    RelNode result = super.visit(project);
+    if (rootForReal && (currentStage == PartialDruidQuery.Stage.AGGREGATE
+                        || currentStage == PartialDruidQuery.Stage.HAVING_FILTER)) {
+      partialDruidQuery = partialDruidQuery.withAggregateProject(project);
+      currentStage = PartialDruidQuery.Stage.AGGREGATE_PROJECT;
+    } else if (currentStage == PartialDruidQuery.Stage.SCAN || currentStage == PartialDruidQuery.Stage.WHERE_FILTER) {
+      partialDruidQuery = partialDruidQuery.withSelectProject(project);
+      currentStage = PartialDruidQuery.Stage.SELECT_PROJECT;
+    } else if (currentStage == PartialDruidQuery.Stage.SELECT_PROJECT) {
+      partialDruidQuery = partialDruidQuery.mergeProject(project);
+      currentStage = PartialDruidQuery.Stage.SELECT_PROJECT;
+    } else if (currentStage == PartialDruidQuery.Stage.SORT) {
+      partialDruidQuery = partialDruidQuery.withSortProject(project);
+      currentStage = PartialDruidQuery.Stage.SORT_PROJECT;
+    } else {
+      queryList.add(partialDruidQuery);
+      queryTables.add(currentTable);
+      partialDruidQuery = PartialDruidQuery.createOuterQuery(partialDruidQuery).withSelectProject(project);
+      currentStage = PartialDruidQuery.Stage.SELECT_PROJECT;
+    }
+    return result;
+  }
+
+  private RelNode visitSort(Sort sort)
+  {
+    isRoot = false;
+    RelNode result = super.visit(sort);
+    if (PartialDruidQuery.Stage.SORT.canFollow(currentStage)) {
+      partialDruidQuery = partialDruidQuery.withSort(sort);
+    } else {
+      queryList.add(partialDruidQuery);
+      queryTables.add(currentTable);
+      partialDruidQuery = PartialDruidQuery.createOuterQuery(partialDruidQuery).withSort(sort);
+    }
+    currentStage = PartialDruidQuery.Stage.SORT;
+    return result;
+  }
+
+  private RelNode visitAggregate(Aggregate aggregate)
+  {
+    isRoot = false;
+    RelNode result = super.visit(aggregate);
+    if (PartialDruidQuery.Stage.AGGREGATE.canFollow(currentStage)) {
+      partialDruidQuery = partialDruidQuery.withAggregate(aggregate);
+    } else {
+      queryList.add(partialDruidQuery);
+      queryTables.add(currentTable);
+      partialDruidQuery = PartialDruidQuery.createOuterQuery(partialDruidQuery).withAggregate(aggregate);
+    }
+    currentStage = PartialDruidQuery.Stage.AGGREGATE;
+    return result;
+  }
+
+  @Override
+  public RelNode visit(RelNode other)
+  {
+    if (other instanceof TableScan) {
+      return visit((TableScan) other);
+    } else if (other instanceof Project) {
+      return visitProject((Project) other);
+    } else if (other instanceof Sort) {
+      return visitSort((Sort) other);
+    } else if (other instanceof Aggregate) {
+      return visitAggregate((Aggregate) other);
+    } else if (other instanceof Filter) {
+      return visitFilter((Filter) other);
+    } else if (other instanceof LogicalValues) {
+      return visit((LogicalValues) other);
+    }
+
+    return super.visit(other);
+  }
+
+  public PartialDruidQuery getPartialDruidQuery()
+  {
+    return partialDruidQuery;
+  }
+
+  public List<PartialDruidQuery> getQueryList()
+  {
+    return queryList;
+  }
+
+  public List<DruidTable> getQueryTables()

Review Comment:
   ## Exposing internal representation
   
   getQueryTables exposes the internal representation stored in field queryTables. The value may be modified [after this call to getQueryTables](1).
   
   [Show more details](https://github.com/apache/druid/security/code-scanning/4928)



##########
sql/src/main/java/org/apache/druid/sql/calcite/planner/DruidQueryGenerator.java:
##########
@@ -0,0 +1,336 @@
+/*
+ * 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.druid.sql.calcite.planner;
+
+import com.google.common.collect.ImmutableList;
+import org.apache.calcite.plan.RelOptTable;
+import org.apache.calcite.rel.RelNode;
+import org.apache.calcite.rel.RelShuttleImpl;
+import org.apache.calcite.rel.core.Aggregate;
+import org.apache.calcite.rel.core.Filter;
+import org.apache.calcite.rel.core.Project;
+import org.apache.calcite.rel.core.Sort;
+import org.apache.calcite.rel.core.TableFunctionScan;
+import org.apache.calcite.rel.core.TableScan;
+import org.apache.calcite.rel.logical.LogicalAggregate;
+import org.apache.calcite.rel.logical.LogicalCorrelate;
+import org.apache.calcite.rel.logical.LogicalExchange;
+import org.apache.calcite.rel.logical.LogicalFilter;
+import org.apache.calcite.rel.logical.LogicalIntersect;
+import org.apache.calcite.rel.logical.LogicalJoin;
+import org.apache.calcite.rel.logical.LogicalMatch;
+import org.apache.calcite.rel.logical.LogicalMinus;
+import org.apache.calcite.rel.logical.LogicalProject;
+import org.apache.calcite.rel.logical.LogicalSort;
+import org.apache.calcite.rel.logical.LogicalUnion;
+import org.apache.calcite.rel.logical.LogicalValues;
+import org.apache.calcite.rex.RexLiteral;
+import org.apache.druid.java.util.common.ISE;
+import org.apache.druid.query.InlineDataSource;
+import org.apache.druid.segment.column.RowSignature;
+import org.apache.druid.sql.calcite.rel.PartialDruidQuery;
+import org.apache.druid.sql.calcite.rel.logical.DruidTableScan;
+import org.apache.druid.sql.calcite.rule.DruidLogicalValuesRule;
+import org.apache.druid.sql.calcite.table.DruidTable;
+import org.apache.druid.sql.calcite.table.InlineTable;
+import org.apache.druid.sql.calcite.table.RowSignatures;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Collectors;
+
+
+/**
+ * Converts a DAG of {@link org.apache.druid.sql.calcite.rel.logical.DruidLogicalNode} convention to a native
+ * Druid query for execution. The convertion is done via a {@link org.apache.calcite.rel.RelShuttle} visitor
+ * implementation.
+ */
+public class DruidQueryGenerator extends RelShuttleImpl
+{
+  private final List<PartialDruidQuery> queryList = new ArrayList<>();
+  private final List<DruidTable> queryTables = new ArrayList<>();
+  private final PlannerContext plannerContext;
+  private PartialDruidQuery partialDruidQuery;
+  private PartialDruidQuery.Stage currentStage = null;
+  private DruidTable currentTable = null;
+  private boolean isRoot = true;
+
+  public DruidQueryGenerator(PlannerContext plannerContext)
+  {
+    this.plannerContext = plannerContext;
+  }
+
+  @Override
+  public RelNode visit(TableScan scan)
+  {
+    if (!(scan instanceof DruidTableScan)) {
+      throw new ISE("Planning hasn't converted logical table scan to druid convention");
+    }
+    DruidTableScan druidTableScan = (DruidTableScan) scan;
+    isRoot = false;
+    RelNode result = super.visit(scan);
+    partialDruidQuery = PartialDruidQuery.create(scan);
+    currentStage = PartialDruidQuery.Stage.SCAN;
+    final RelOptTable table = scan.getTable();
+    final DruidTable druidTable = table.unwrap(DruidTable.class);
+    if (druidTable != null) {
+      currentTable = druidTable;
+    }
+    if (druidTableScan.getProject() != null) {
+      partialDruidQuery = partialDruidQuery.withSelectProject(druidTableScan.getProject());
+      currentStage = PartialDruidQuery.Stage.SELECT_PROJECT;
+    }
+    return result;
+  }
+
+  @Override
+  public RelNode visit(TableFunctionScan scan)
+  {
+    return null;
+  }
+
+  @Override
+  public RelNode visit(LogicalValues values)
+  {
+    isRoot = false;
+    RelNode result = super.visit(values);
+    final List<ImmutableList<RexLiteral>> tuples = values.getTuples();
+    final List<Object[]> objectTuples = tuples
+        .stream()
+        .map(tuple -> tuple
+            .stream()
+            .map(v -> DruidLogicalValuesRule.getValueFromLiteral(v, plannerContext))
+            .collect(Collectors.toList())
+            .toArray(new Object[0])
+        )
+        .collect(Collectors.toList());
+    RowSignature rowSignature = RowSignatures.fromRelDataType(
+        values.getRowType().getFieldNames(),
+        values.getRowType()
+    );
+    currentTable = new InlineTable(InlineDataSource.fromIterable(objectTuples, rowSignature));
+    if (currentStage == null) {
+      partialDruidQuery = PartialDruidQuery.create(values);
+      currentStage = PartialDruidQuery.Stage.SCAN;
+    } else {
+      throw new ISE("Values node found at non leaf node in the plan");
+    }
+    return result;
+  }
+
+  @Override
+  public RelNode visit(LogicalFilter filter)
+  {
+    return visitFilter(filter);
+  }
+
+  public RelNode visitFilter(Filter filter)
+  {
+    isRoot = false;
+    RelNode result = super.visit(filter);
+    if (currentStage == PartialDruidQuery.Stage.AGGREGATE) {
+      partialDruidQuery = partialDruidQuery.withHavingFilter(filter);
+      currentStage = PartialDruidQuery.Stage.HAVING_FILTER;
+    } else if (currentStage == PartialDruidQuery.Stage.SCAN) {
+      partialDruidQuery = partialDruidQuery.withWhereFilter(filter);
+      currentStage = PartialDruidQuery.Stage.WHERE_FILTER;
+    } else if (currentStage == PartialDruidQuery.Stage.SELECT_PROJECT) {
+      PartialDruidQuery old = partialDruidQuery;
+      partialDruidQuery = PartialDruidQuery.create(old.getScan());
+      partialDruidQuery = partialDruidQuery.withWhereFilter(filter);
+      partialDruidQuery = partialDruidQuery.withSelectProject(old.getSelectProject());
+      currentStage = PartialDruidQuery.Stage.SELECT_PROJECT;
+    } else {
+      queryList.add(partialDruidQuery);
+      queryTables.add(currentTable);
+      partialDruidQuery = PartialDruidQuery.createOuterQuery(partialDruidQuery).withWhereFilter(filter);
+      currentStage = PartialDruidQuery.Stage.WHERE_FILTER;
+    }
+    return result;
+  }
+
+  @Override
+  public RelNode visit(LogicalProject project)
+  {
+    return visitProject(project);
+  }
+
+  @Override
+  public RelNode visit(LogicalJoin join)
+  {
+    throw new UnsupportedOperationException("Found join");
+  }
+
+  @Override
+  public RelNode visit(LogicalCorrelate correlate)
+  {
+    return null;
+  }
+
+  @Override
+  public RelNode visit(LogicalUnion union)
+  {
+    throw new UnsupportedOperationException("Found union");
+  }
+
+  @Override
+  public RelNode visit(LogicalIntersect intersect)
+  {
+    return null;
+  }
+
+  @Override
+  public RelNode visit(LogicalMinus minus)
+  {
+    return null;
+  }
+
+  @Override
+  public RelNode visit(LogicalAggregate aggregate)
+  {
+    isRoot = false;
+    RelNode result = super.visit(aggregate);
+    if (PartialDruidQuery.Stage.AGGREGATE.canFollow(currentStage)) {
+      partialDruidQuery = partialDruidQuery.withAggregate(aggregate);
+    } else {
+      queryList.add(partialDruidQuery);
+      queryTables.add(currentTable);
+      partialDruidQuery = PartialDruidQuery.createOuterQuery(partialDruidQuery).withAggregate(aggregate);
+    }
+    currentStage = PartialDruidQuery.Stage.AGGREGATE;
+    return result;
+  }
+
+  @Override
+  public RelNode visit(LogicalMatch match)
+  {
+    return null;
+  }
+
+  @Override
+  public RelNode visit(LogicalSort sort)
+  {
+    return visitSort(sort);
+  }
+
+  @Override
+  public RelNode visit(LogicalExchange exchange)
+  {
+    return null;
+  }
+
+  private RelNode visitProject(Project project)
+  {
+    boolean rootForReal = isRoot;
+    isRoot = false;
+    RelNode result = super.visit(project);
+    if (rootForReal && (currentStage == PartialDruidQuery.Stage.AGGREGATE
+                        || currentStage == PartialDruidQuery.Stage.HAVING_FILTER)) {
+      partialDruidQuery = partialDruidQuery.withAggregateProject(project);
+      currentStage = PartialDruidQuery.Stage.AGGREGATE_PROJECT;
+    } else if (currentStage == PartialDruidQuery.Stage.SCAN || currentStage == PartialDruidQuery.Stage.WHERE_FILTER) {
+      partialDruidQuery = partialDruidQuery.withSelectProject(project);
+      currentStage = PartialDruidQuery.Stage.SELECT_PROJECT;
+    } else if (currentStage == PartialDruidQuery.Stage.SELECT_PROJECT) {
+      partialDruidQuery = partialDruidQuery.mergeProject(project);
+      currentStage = PartialDruidQuery.Stage.SELECT_PROJECT;
+    } else if (currentStage == PartialDruidQuery.Stage.SORT) {
+      partialDruidQuery = partialDruidQuery.withSortProject(project);
+      currentStage = PartialDruidQuery.Stage.SORT_PROJECT;
+    } else {
+      queryList.add(partialDruidQuery);
+      queryTables.add(currentTable);
+      partialDruidQuery = PartialDruidQuery.createOuterQuery(partialDruidQuery).withSelectProject(project);
+      currentStage = PartialDruidQuery.Stage.SELECT_PROJECT;
+    }
+    return result;
+  }
+
+  private RelNode visitSort(Sort sort)
+  {
+    isRoot = false;
+    RelNode result = super.visit(sort);
+    if (PartialDruidQuery.Stage.SORT.canFollow(currentStage)) {
+      partialDruidQuery = partialDruidQuery.withSort(sort);
+    } else {
+      queryList.add(partialDruidQuery);
+      queryTables.add(currentTable);
+      partialDruidQuery = PartialDruidQuery.createOuterQuery(partialDruidQuery).withSort(sort);
+    }
+    currentStage = PartialDruidQuery.Stage.SORT;
+    return result;
+  }
+
+  private RelNode visitAggregate(Aggregate aggregate)
+  {
+    isRoot = false;
+    RelNode result = super.visit(aggregate);
+    if (PartialDruidQuery.Stage.AGGREGATE.canFollow(currentStage)) {
+      partialDruidQuery = partialDruidQuery.withAggregate(aggregate);
+    } else {
+      queryList.add(partialDruidQuery);
+      queryTables.add(currentTable);
+      partialDruidQuery = PartialDruidQuery.createOuterQuery(partialDruidQuery).withAggregate(aggregate);
+    }
+    currentStage = PartialDruidQuery.Stage.AGGREGATE;
+    return result;
+  }
+
+  @Override
+  public RelNode visit(RelNode other)
+  {
+    if (other instanceof TableScan) {

Review Comment:
   ## Chain of 'instanceof' tests
   
   This if block performs a chain of 6 type tests - consider alternatives, e.g. polymorphism or the visitor pattern.
   
   [Show more details](https://github.com/apache/druid/security/code-scanning/4930)



##########
sql/src/main/java/org/apache/druid/sql/calcite/rel/logical/DruidTableScan.java:
##########
@@ -0,0 +1,111 @@
+/*
+ * 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.druid.sql.calcite.rel.logical;
+
+import com.google.common.collect.ImmutableList;
+import org.apache.calcite.plan.RelOptCluster;
+import org.apache.calcite.plan.RelOptCost;
+import org.apache.calcite.plan.RelOptPlanner;
+import org.apache.calcite.plan.RelOptTable;
+import org.apache.calcite.plan.RelTraitSet;
+import org.apache.calcite.rel.RelCollationTraitDef;
+import org.apache.calcite.rel.RelNode;
+import org.apache.calcite.rel.RelWriter;
+import org.apache.calcite.rel.core.Project;
+import org.apache.calcite.rel.core.TableScan;
+import org.apache.calcite.rel.metadata.RelMetadataQuery;
+import org.apache.calcite.rel.type.RelDataType;
+import org.apache.calcite.schema.Table;
+
+import java.util.List;
+
+/**
+ * {@link DruidLogicalNode} convention node for {@link TableScan} plan node.
+ */
+public class DruidTableScan extends TableScan implements DruidLogicalNode

Review Comment:
   ## No clone method
   
   No clone method, yet implements Cloneable.
   
   [Show more details](https://github.com/apache/druid/security/code-scanning/4932)



##########
sql/src/main/java/org/apache/druid/sql/calcite/planner/DruidQueryGenerator.java:
##########
@@ -0,0 +1,336 @@
+/*
+ * 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.druid.sql.calcite.planner;
+
+import com.google.common.collect.ImmutableList;
+import org.apache.calcite.plan.RelOptTable;
+import org.apache.calcite.rel.RelNode;
+import org.apache.calcite.rel.RelShuttleImpl;
+import org.apache.calcite.rel.core.Aggregate;
+import org.apache.calcite.rel.core.Filter;
+import org.apache.calcite.rel.core.Project;
+import org.apache.calcite.rel.core.Sort;
+import org.apache.calcite.rel.core.TableFunctionScan;
+import org.apache.calcite.rel.core.TableScan;
+import org.apache.calcite.rel.logical.LogicalAggregate;
+import org.apache.calcite.rel.logical.LogicalCorrelate;
+import org.apache.calcite.rel.logical.LogicalExchange;
+import org.apache.calcite.rel.logical.LogicalFilter;
+import org.apache.calcite.rel.logical.LogicalIntersect;
+import org.apache.calcite.rel.logical.LogicalJoin;
+import org.apache.calcite.rel.logical.LogicalMatch;
+import org.apache.calcite.rel.logical.LogicalMinus;
+import org.apache.calcite.rel.logical.LogicalProject;
+import org.apache.calcite.rel.logical.LogicalSort;
+import org.apache.calcite.rel.logical.LogicalUnion;
+import org.apache.calcite.rel.logical.LogicalValues;
+import org.apache.calcite.rex.RexLiteral;
+import org.apache.druid.java.util.common.ISE;
+import org.apache.druid.query.InlineDataSource;
+import org.apache.druid.segment.column.RowSignature;
+import org.apache.druid.sql.calcite.rel.PartialDruidQuery;
+import org.apache.druid.sql.calcite.rel.logical.DruidTableScan;
+import org.apache.druid.sql.calcite.rule.DruidLogicalValuesRule;
+import org.apache.druid.sql.calcite.table.DruidTable;
+import org.apache.druid.sql.calcite.table.InlineTable;
+import org.apache.druid.sql.calcite.table.RowSignatures;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Collectors;
+
+
+/**
+ * Converts a DAG of {@link org.apache.druid.sql.calcite.rel.logical.DruidLogicalNode} convention to a native
+ * Druid query for execution. The convertion is done via a {@link org.apache.calcite.rel.RelShuttle} visitor
+ * implementation.
+ */
+public class DruidQueryGenerator extends RelShuttleImpl
+{
+  private final List<PartialDruidQuery> queryList = new ArrayList<>();
+  private final List<DruidTable> queryTables = new ArrayList<>();
+  private final PlannerContext plannerContext;
+  private PartialDruidQuery partialDruidQuery;
+  private PartialDruidQuery.Stage currentStage = null;
+  private DruidTable currentTable = null;
+  private boolean isRoot = true;
+
+  public DruidQueryGenerator(PlannerContext plannerContext)
+  {
+    this.plannerContext = plannerContext;
+  }
+
+  @Override
+  public RelNode visit(TableScan scan)
+  {
+    if (!(scan instanceof DruidTableScan)) {
+      throw new ISE("Planning hasn't converted logical table scan to druid convention");
+    }
+    DruidTableScan druidTableScan = (DruidTableScan) scan;
+    isRoot = false;
+    RelNode result = super.visit(scan);
+    partialDruidQuery = PartialDruidQuery.create(scan);
+    currentStage = PartialDruidQuery.Stage.SCAN;
+    final RelOptTable table = scan.getTable();
+    final DruidTable druidTable = table.unwrap(DruidTable.class);
+    if (druidTable != null) {
+      currentTable = druidTable;
+    }
+    if (druidTableScan.getProject() != null) {
+      partialDruidQuery = partialDruidQuery.withSelectProject(druidTableScan.getProject());
+      currentStage = PartialDruidQuery.Stage.SELECT_PROJECT;
+    }
+    return result;
+  }
+
+  @Override
+  public RelNode visit(TableFunctionScan scan)
+  {
+    return null;
+  }
+
+  @Override
+  public RelNode visit(LogicalValues values)
+  {
+    isRoot = false;
+    RelNode result = super.visit(values);
+    final List<ImmutableList<RexLiteral>> tuples = values.getTuples();
+    final List<Object[]> objectTuples = tuples
+        .stream()
+        .map(tuple -> tuple
+            .stream()
+            .map(v -> DruidLogicalValuesRule.getValueFromLiteral(v, plannerContext))
+            .collect(Collectors.toList())
+            .toArray(new Object[0])
+        )
+        .collect(Collectors.toList());
+    RowSignature rowSignature = RowSignatures.fromRelDataType(
+        values.getRowType().getFieldNames(),
+        values.getRowType()
+    );
+    currentTable = new InlineTable(InlineDataSource.fromIterable(objectTuples, rowSignature));
+    if (currentStage == null) {
+      partialDruidQuery = PartialDruidQuery.create(values);
+      currentStage = PartialDruidQuery.Stage.SCAN;
+    } else {
+      throw new ISE("Values node found at non leaf node in the plan");
+    }
+    return result;
+  }
+
+  @Override
+  public RelNode visit(LogicalFilter filter)
+  {
+    return visitFilter(filter);
+  }
+
+  public RelNode visitFilter(Filter filter)
+  {
+    isRoot = false;
+    RelNode result = super.visit(filter);
+    if (currentStage == PartialDruidQuery.Stage.AGGREGATE) {
+      partialDruidQuery = partialDruidQuery.withHavingFilter(filter);
+      currentStage = PartialDruidQuery.Stage.HAVING_FILTER;
+    } else if (currentStage == PartialDruidQuery.Stage.SCAN) {
+      partialDruidQuery = partialDruidQuery.withWhereFilter(filter);
+      currentStage = PartialDruidQuery.Stage.WHERE_FILTER;
+    } else if (currentStage == PartialDruidQuery.Stage.SELECT_PROJECT) {
+      PartialDruidQuery old = partialDruidQuery;
+      partialDruidQuery = PartialDruidQuery.create(old.getScan());
+      partialDruidQuery = partialDruidQuery.withWhereFilter(filter);
+      partialDruidQuery = partialDruidQuery.withSelectProject(old.getSelectProject());
+      currentStage = PartialDruidQuery.Stage.SELECT_PROJECT;
+    } else {
+      queryList.add(partialDruidQuery);
+      queryTables.add(currentTable);
+      partialDruidQuery = PartialDruidQuery.createOuterQuery(partialDruidQuery).withWhereFilter(filter);
+      currentStage = PartialDruidQuery.Stage.WHERE_FILTER;
+    }
+    return result;
+  }
+
+  @Override
+  public RelNode visit(LogicalProject project)
+  {
+    return visitProject(project);
+  }
+
+  @Override
+  public RelNode visit(LogicalJoin join)
+  {
+    throw new UnsupportedOperationException("Found join");
+  }
+
+  @Override
+  public RelNode visit(LogicalCorrelate correlate)
+  {
+    return null;
+  }
+
+  @Override
+  public RelNode visit(LogicalUnion union)
+  {
+    throw new UnsupportedOperationException("Found union");
+  }
+
+  @Override
+  public RelNode visit(LogicalIntersect intersect)
+  {
+    return null;
+  }
+
+  @Override
+  public RelNode visit(LogicalMinus minus)
+  {
+    return null;
+  }
+
+  @Override
+  public RelNode visit(LogicalAggregate aggregate)
+  {
+    isRoot = false;
+    RelNode result = super.visit(aggregate);
+    if (PartialDruidQuery.Stage.AGGREGATE.canFollow(currentStage)) {
+      partialDruidQuery = partialDruidQuery.withAggregate(aggregate);
+    } else {
+      queryList.add(partialDruidQuery);
+      queryTables.add(currentTable);
+      partialDruidQuery = PartialDruidQuery.createOuterQuery(partialDruidQuery).withAggregate(aggregate);
+    }
+    currentStage = PartialDruidQuery.Stage.AGGREGATE;
+    return result;
+  }
+
+  @Override
+  public RelNode visit(LogicalMatch match)
+  {
+    return null;
+  }
+
+  @Override
+  public RelNode visit(LogicalSort sort)
+  {
+    return visitSort(sort);
+  }
+
+  @Override
+  public RelNode visit(LogicalExchange exchange)
+  {
+    return null;
+  }
+
+  private RelNode visitProject(Project project)
+  {
+    boolean rootForReal = isRoot;
+    isRoot = false;
+    RelNode result = super.visit(project);
+    if (rootForReal && (currentStage == PartialDruidQuery.Stage.AGGREGATE
+                        || currentStage == PartialDruidQuery.Stage.HAVING_FILTER)) {
+      partialDruidQuery = partialDruidQuery.withAggregateProject(project);
+      currentStage = PartialDruidQuery.Stage.AGGREGATE_PROJECT;
+    } else if (currentStage == PartialDruidQuery.Stage.SCAN || currentStage == PartialDruidQuery.Stage.WHERE_FILTER) {
+      partialDruidQuery = partialDruidQuery.withSelectProject(project);
+      currentStage = PartialDruidQuery.Stage.SELECT_PROJECT;
+    } else if (currentStage == PartialDruidQuery.Stage.SELECT_PROJECT) {
+      partialDruidQuery = partialDruidQuery.mergeProject(project);
+      currentStage = PartialDruidQuery.Stage.SELECT_PROJECT;
+    } else if (currentStage == PartialDruidQuery.Stage.SORT) {
+      partialDruidQuery = partialDruidQuery.withSortProject(project);
+      currentStage = PartialDruidQuery.Stage.SORT_PROJECT;
+    } else {
+      queryList.add(partialDruidQuery);
+      queryTables.add(currentTable);
+      partialDruidQuery = PartialDruidQuery.createOuterQuery(partialDruidQuery).withSelectProject(project);
+      currentStage = PartialDruidQuery.Stage.SELECT_PROJECT;
+    }
+    return result;
+  }
+
+  private RelNode visitSort(Sort sort)
+  {
+    isRoot = false;
+    RelNode result = super.visit(sort);
+    if (PartialDruidQuery.Stage.SORT.canFollow(currentStage)) {
+      partialDruidQuery = partialDruidQuery.withSort(sort);
+    } else {
+      queryList.add(partialDruidQuery);
+      queryTables.add(currentTable);
+      partialDruidQuery = PartialDruidQuery.createOuterQuery(partialDruidQuery).withSort(sort);
+    }
+    currentStage = PartialDruidQuery.Stage.SORT;
+    return result;
+  }
+
+  private RelNode visitAggregate(Aggregate aggregate)
+  {
+    isRoot = false;
+    RelNode result = super.visit(aggregate);
+    if (PartialDruidQuery.Stage.AGGREGATE.canFollow(currentStage)) {
+      partialDruidQuery = partialDruidQuery.withAggregate(aggregate);
+    } else {
+      queryList.add(partialDruidQuery);
+      queryTables.add(currentTable);
+      partialDruidQuery = PartialDruidQuery.createOuterQuery(partialDruidQuery).withAggregate(aggregate);
+    }
+    currentStage = PartialDruidQuery.Stage.AGGREGATE;
+    return result;
+  }
+
+  @Override
+  public RelNode visit(RelNode other)
+  {
+    if (other instanceof TableScan) {
+      return visit((TableScan) other);
+    } else if (other instanceof Project) {
+      return visitProject((Project) other);
+    } else if (other instanceof Sort) {
+      return visitSort((Sort) other);
+    } else if (other instanceof Aggregate) {
+      return visitAggregate((Aggregate) other);
+    } else if (other instanceof Filter) {
+      return visitFilter((Filter) other);
+    } else if (other instanceof LogicalValues) {
+      return visit((LogicalValues) other);
+    }
+
+    return super.visit(other);
+  }
+
+  public PartialDruidQuery getPartialDruidQuery()
+  {
+    return partialDruidQuery;
+  }
+
+  public List<PartialDruidQuery> getQueryList()

Review Comment:
   ## Exposing internal representation
   
   getQueryList exposes the internal representation stored in field queryList. The value may be modified [after this call to getQueryList](1).
   
   [Show more details](https://github.com/apache/druid/security/code-scanning/4929)



##########
sql/src/main/java/org/apache/druid/sql/calcite/rel/logical/DruidAggregate.java:
##########
@@ -0,0 +1,101 @@
+/*
+ * 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.druid.sql.calcite.rel.logical;
+
+import org.apache.calcite.plan.RelOptCluster;
+import org.apache.calcite.plan.RelOptCost;
+import org.apache.calcite.plan.RelOptPlanner;
+import org.apache.calcite.plan.RelTraitSet;
+import org.apache.calcite.rel.RelNode;
+import org.apache.calcite.rel.RelWriter;
+import org.apache.calcite.rel.core.Aggregate;
+import org.apache.calcite.rel.core.AggregateCall;
+import org.apache.calcite.rel.metadata.RelMetadataQuery;
+import org.apache.calcite.util.ImmutableBitSet;
+import org.apache.druid.sql.calcite.planner.PlannerContext;
+import org.apache.druid.sql.calcite.rel.CostEstimates;
+
+import java.util.List;
+
+/**
+ * {@link DruidLogicalNode} convention node for {@link Aggregate} plan node.
+ */
+public class DruidAggregate extends Aggregate implements DruidLogicalNode

Review Comment:
   ## No clone method
   
   No clone method, yet implements Cloneable.
   
   [Show more details](https://github.com/apache/druid/security/code-scanning/4931)



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