[GitHub] [druid] gianm commented on a change in pull request #12145: add EARLIEST_BY/LATEST_BY to make EARLIEST/LATEST function signatures less ambiguous

[GitBox <gi...@apache.org>]

gianm commented on a change in pull request #12145:
URL: https://github.com/apache/druid/pull/12145#discussion_r782660443



##########
File path: sql/src/main/java/org/apache/druid/sql/calcite/aggregation/builtin/EarliestLatestBySqlAggregator.java
##########
@@ -0,0 +1,180 @@
+/*
+ * 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.aggregation.builtin;
+
+import org.apache.calcite.rel.core.AggregateCall;
+import org.apache.calcite.rel.core.Project;
+import org.apache.calcite.rex.RexBuilder;
+import org.apache.calcite.rex.RexLiteral;
+import org.apache.calcite.rex.RexNode;
+import org.apache.calcite.sql.SqlAggFunction;
+import org.apache.calcite.sql.SqlFunctionCategory;
+import org.apache.calcite.sql.SqlKind;
+import org.apache.calcite.sql.type.InferTypes;
+import org.apache.calcite.sql.type.OperandTypes;
+import org.apache.calcite.sql.type.SqlReturnTypeInference;
+import org.apache.calcite.util.Optionality;
+import org.apache.druid.java.util.common.IAE;
+import org.apache.druid.java.util.common.ISE;
+import org.apache.druid.java.util.common.StringUtils;
+import org.apache.druid.query.aggregation.AggregatorFactory;
+import org.apache.druid.query.aggregation.post.FinalizingFieldAccessPostAggregator;
+import org.apache.druid.segment.column.ColumnType;
+import org.apache.druid.segment.column.RowSignature;
+import org.apache.druid.sql.calcite.aggregation.Aggregation;
+import org.apache.druid.sql.calcite.aggregation.SqlAggregator;
+import org.apache.druid.sql.calcite.expression.DruidExpression;
+import org.apache.druid.sql.calcite.expression.Expressions;
+import org.apache.druid.sql.calcite.planner.Calcites;
+import org.apache.druid.sql.calcite.planner.PlannerContext;
+import org.apache.druid.sql.calcite.rel.VirtualColumnRegistry;
+
+import javax.annotation.Nullable;
+import java.util.Collections;
+import java.util.List;
+import java.util.stream.Collectors;
+
+public class EarliestLatestBySqlAggregator implements SqlAggregator
+{
+  public static final SqlAggregator EARLIEST_BY = new EarliestLatestBySqlAggregator(EarliestLatestAnySqlAggregator.AggregatorType.EARLIEST);
+  public static final SqlAggregator LATEST_BY = new EarliestLatestBySqlAggregator(EarliestLatestAnySqlAggregator.AggregatorType.LATEST);
+
+  private final EarliestLatestAnySqlAggregator.AggregatorType aggregatorType;
+  private final SqlAggFunction function;
+
+  private EarliestLatestBySqlAggregator(final EarliestLatestAnySqlAggregator.AggregatorType aggregatorType)
+  {
+    this.aggregatorType = aggregatorType;
+    this.function = new EarliestByLatestBySqlAggFunction(aggregatorType);
+  }
+
+  @Override
+  public SqlAggFunction calciteFunction()
+  {
+    return function;
+  }
+
+  @Nullable
+  @Override
+  public Aggregation toDruidAggregation(
+      final PlannerContext plannerContext,
+      final RowSignature rowSignature,
+      final VirtualColumnRegistry virtualColumnRegistry,
+      final RexBuilder rexBuilder,
+      final String name,
+      final AggregateCall aggregateCall,
+      final Project project,
+      final List<Aggregation> existingAggregations,
+      final boolean finalizeAggregations
+  )
+  {
+    final List<RexNode> rexNodes = aggregateCall
+        .getArgList()
+        .stream()
+        .map(i -> Expressions.fromFieldAccess(rowSignature, project, i))
+        .collect(Collectors.toList());
+
+    final List<DruidExpression> args = Expressions.toDruidExpressions(plannerContext, rowSignature, rexNodes);
+
+    if (args == null) {
+      return null;
+    }
+
+    final String aggregatorName = finalizeAggregations ? Calcites.makePrefixedName(name, "a") : name;
+    final ColumnType outputType = Calcites.getColumnTypeForRelDataType(aggregateCall.getType());
+    if (outputType == null) {
+      throw new ISE(
+          "Cannot translate output sqlTypeName[%s] to Druid type for aggregator[%s]",
+          aggregateCall.getType().getSqlTypeName(),
+          aggregateCall.getName()
+      );
+    }
+
+    final String fieldName = EarliestLatestAnySqlAggregator.getColumnName(plannerContext, virtualColumnRegistry, args.get(0), rexNodes.get(0));
+
+    final AggregatorFactory theAggFactory;
+    switch (args.size()) {
+      case 2:
+        theAggFactory = aggregatorType.createAggregatorFactory(
+            aggregatorName,
+            fieldName,
+            EarliestLatestAnySqlAggregator.getColumnName(plannerContext, virtualColumnRegistry, args.get(1), rexNodes.get(1)),
+            outputType,
+            -1
+        );
+        break;
+      case 3:
+        theAggFactory = aggregatorType.createAggregatorFactory(
+            aggregatorName,
+            fieldName,
+            EarliestLatestAnySqlAggregator.getColumnName(plannerContext, virtualColumnRegistry, args.get(2), rexNodes.get(2)),
+            outputType,
+            RexLiteral.intValue(rexNodes.get(1))
+        );
+        break;
+      default:
+        throw new IAE(
+            "aggregation[%s], Invalid number of arguments[%,d] to [%s] operator",
+            aggregatorName,
+            args.size(),
+            aggregatorType.name()
+        );
+    }
+
+    return Aggregation.create(
+        Collections.singletonList(theAggFactory),
+        finalizeAggregations ? new FinalizingFieldAccessPostAggregator(name, aggregatorName) : null
+    );
+  }
+
+  private static class EarliestByLatestBySqlAggFunction extends SqlAggFunction
+  {
+    private static final SqlReturnTypeInference EARLIEST_LATEST_ARG0_RETURN_TYPE_INFERENCE =
+        new EarliestLatestAnySqlAggregator.EarliestLatestReturnTypeInference(0);
+
+    EarliestByLatestBySqlAggFunction(EarliestLatestAnySqlAggregator.AggregatorType aggregatorType)
+    {
+      super(
+          StringUtils.format("%s_BY", aggregatorType.name()),
+          null,
+          SqlKind.OTHER_FUNCTION,
+          EARLIEST_LATEST_ARG0_RETURN_TYPE_INFERENCE,
+          InferTypes.RETURN_TYPE,
+          OperandTypes.or(
+              OperandTypes.sequence(
+                  "'" + aggregatorType.name() + "(expr, timeColumn)'\n",
+                  OperandTypes.ANY,
+                  OperandTypes.NUMERIC

Review comment:
       IMO we should allow either NUMERIC or TIMESTAMP here.




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