[GitHub] [incubator-druid] gianm commented on a change in pull request #8815: SQL: EARLIEST, LATEST aggregators.

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

gianm commented on a change in pull request #8815: SQL: EARLIEST, LATEST aggregators.
URL: https://github.com/apache/incubator-druid/pull/8815#discussion_r343290083
 
 

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 File path: sql/src/main/java/org/apache/druid/sql/calcite/aggregation/builtin/EarliestLatestSqlAggregator.java
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+/*
+ * 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.ReturnTypes;
+import org.apache.calcite.sql.type.SqlTypeName;
+import org.apache.druid.java.util.common.ISE;
+import org.apache.druid.query.aggregation.AggregatorFactory;
+import org.apache.druid.query.aggregation.first.DoubleFirstAggregatorFactory;
+import org.apache.druid.query.aggregation.first.FloatFirstAggregatorFactory;
+import org.apache.druid.query.aggregation.first.LongFirstAggregatorFactory;
+import org.apache.druid.query.aggregation.first.StringFirstAggregatorFactory;
+import org.apache.druid.query.aggregation.last.DoubleLastAggregatorFactory;
+import org.apache.druid.query.aggregation.last.FloatLastAggregatorFactory;
+import org.apache.druid.query.aggregation.last.LongLastAggregatorFactory;
+import org.apache.druid.query.aggregation.last.StringLastAggregatorFactory;
+import org.apache.druid.query.aggregation.post.FinalizingFieldAccessPostAggregator;
+import org.apache.druid.segment.VirtualColumn;
+import org.apache.druid.segment.column.ValueType;
+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 org.apache.druid.sql.calcite.table.RowSignature;
+
+import javax.annotation.Nullable;
+import java.util.Collections;
+import java.util.List;
+import java.util.Objects;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class EarliestLatestSqlAggregator implements SqlAggregator
+{
+  public static final SqlAggregator EARLIEST = new EarliestLatestSqlAggregator(EarliestOrLatest.EARLIEST);
+  public static final SqlAggregator LATEST = new EarliestLatestSqlAggregator(EarliestOrLatest.LATEST);
+
+  enum EarliestOrLatest
+  {
+    EARLIEST {
+      @Override
+      AggregatorFactory createAggregatorFactory(String name, String fieldName, ValueType type, int maxStringBytes)
+      {
+        switch (type) {
+          case LONG:
+            return new LongFirstAggregatorFactory(name, fieldName);
+          case FLOAT:
+            return new FloatFirstAggregatorFactory(name, fieldName);
+          case DOUBLE:
+            return new DoubleFirstAggregatorFactory(name, fieldName);
+          case STRING:
+            return new StringFirstAggregatorFactory(name, fieldName, maxStringBytes);
 
 Review comment:
   The validation sounds like a nice addition. I can add it after #8834 is merged. Right now, this patch conflicts with that one, and is blocked on it.
   
   I think if `maxStringBytes` is 0 you'd expect to get an empty string. A little goofy but technically correct. The best kind of correct :)

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