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https://issues.apache.org/jira/browse/FLINK-3475?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15823451#comment-15823451
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ASF GitHub Bot commented on FLINK-3475:
---------------------------------------
Github user wuchong commented on a diff in the pull request:
https://github.com/apache/flink/pull/3111#discussion_r96160329
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/plan/rules/dataSet/FlinkAggregateExpandDistinctAggregatesRule.java
---
@@ -0,0 +1,1144 @@
+/*
+ * 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.flink.table.plan.rules.dataSet;
+
+import org.apache.calcite.plan.Contexts;
+import org.apache.calcite.plan.RelOptCluster;
+import org.apache.calcite.plan.RelOptRule;
+import org.apache.calcite.plan.RelOptRuleCall;
+import org.apache.calcite.rel.RelNode;
+import org.apache.calcite.rel.core.Aggregate;
+import org.apache.calcite.rel.core.AggregateCall;
+import org.apache.calcite.rel.core.JoinRelType;
+import org.apache.calcite.rel.core.RelFactories;
+import org.apache.calcite.rel.logical.LogicalAggregate;
+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.rex.RexBuilder;
+import org.apache.calcite.rex.RexInputRef;
+import org.apache.calcite.rex.RexNode;
+import org.apache.calcite.sql.SqlAggFunction;
+import org.apache.calcite.sql.fun.SqlCountAggFunction;
+import org.apache.calcite.sql.fun.SqlMinMaxAggFunction;
+import org.apache.calcite.sql.fun.SqlStdOperatorTable;
+import org.apache.calcite.sql.fun.SqlSumAggFunction;
+import org.apache.calcite.sql.fun.SqlSumEmptyIsZeroAggFunction;
+import org.apache.calcite.sql.type.SqlTypeName;
+import org.apache.calcite.tools.RelBuilder;
+import org.apache.calcite.tools.RelBuilderFactory;
+import org.apache.calcite.util.ImmutableBitSet;
+import org.apache.calcite.util.ImmutableIntList;
+import org.apache.calcite.util.Pair;
+import org.apache.calcite.util.Util;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Iterables;
+import com.google.common.collect.Lists;
+
+import java.math.BigDecimal;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.SortedSet;
+import java.util.TreeSet;
+
+/**
+ * Planner rule that expands distinct aggregates
+ * (such as {@code COUNT(DISTINCT x)}) from a
+ * {@link org.apache.calcite.rel.logical.LogicalAggregate}.
+ *
+ * <p>How this is done depends upon the arguments to the function. If all
+ * functions have the same argument
+ * (e.g. {@code COUNT(DISTINCT x), SUM(DISTINCT x)} both have the argument
+ * {@code x}) then one extra {@link org.apache.calcite.rel.core.Aggregate}
is
+ * sufficient.
+ *
+ * <p>If there are multiple arguments
+ * (e.g. {@code COUNT(DISTINCT x), COUNT(DISTINCT y)})
+ * the rule creates separate {@code Aggregate}s and combines using a
+ * {@link org.apache.calcite.rel.core.Join}.
+ */
+public final class FlinkAggregateExpandDistinctAggregatesRule extends
RelOptRule {
--- End diff --
I would like to move this class to `org.apache.flink.table.calcite`
package, and add a comment to the top of the class to annotate this is a
temporary solution and should be removed later, such as
>This is a copy of Calcite's [[AggregateExpandDistinctAggregatesRule]] with
a quick fix to avoid some bad case mentioned in CALCITE-1558. Should drop it
and use calcite's [[AggregateExpandDistinctAggregatesRule]] when upgrade to
calcite 1.12 (above).
> DISTINCT aggregate function support for SQL queries
> ---------------------------------------------------
>
> Key: FLINK-3475
> URL: https://issues.apache.org/jira/browse/FLINK-3475
> Project: Flink
> Issue Type: New Feature
> Components: Table API & SQL
> Reporter: Chengxiang Li
> Assignee: Zhenghua Gao
>
> DISTINCT aggregate function may be able to reuse the aggregate function
> instead of separate implementation, and let Flink runtime take care of
> duplicate records.
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