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https://issues.apache.org/jira/browse/DRILL-3962?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18031108#comment-18031108
]
ASF GitHub Bot commented on DRILL-3962:
---------------------------------------
rymarm commented on code in PR #3026:
URL: https://github.com/apache/drill/pull/3026#discussion_r2444427085
##########
exec/java-exec/src/main/java/org/apache/drill/exec/planner/logical/DrillAggregateExpandGroupingSetsRule.java:
##########
@@ -0,0 +1,475 @@
+/*
+ * 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.drill.exec.planner.logical;
+
+import com.google.common.collect.ImmutableList;
+import org.apache.calcite.plan.RelOptCluster;
+import org.apache.calcite.plan.RelOptRule;
+import org.apache.calcite.plan.RelOptRuleCall;
+import org.apache.calcite.rel.InvalidRelException;
+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.logical.LogicalAggregate;
+import org.apache.calcite.rel.type.RelDataTypeFactory;
+import org.apache.calcite.rex.RexBuilder;
+import org.apache.calcite.rex.RexNode;
+import org.apache.calcite.sql.SqlKind;
+import org.apache.calcite.sql.fun.SqlStdOperatorTable;
+import org.apache.calcite.sql.type.SqlTypeName;
+import org.apache.calcite.util.ImmutableBitSet;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Planner rule that expands GROUPING SETS, ROLLUP, and CUBE into a UNION ALL
+ * of multiple aggregates, each with a single grouping set.
+ *
+ * This rule converts:
+ * SELECT a, b, SUM(c) FROM t GROUP BY GROUPING SETS ((a, b), (a), ())
+ *
+ * Into:
+ * SELECT a, b, SUM(c), 0 AS $g FROM t GROUP BY a, b
+ * UNION ALL
+ * SELECT a, null, SUM(c), 1 AS $g FROM t GROUP BY a
+ * UNION ALL
+ * SELECT null, null, SUM(c), 3 AS $g FROM t GROUP BY ()
+ *
+ * The $g column is the grouping ID that can be used by GROUPING() and
GROUPING_ID() functions.
+ * Currently, the $g column is generated internally but stripped from the
final output.
+ */
+public class DrillAggregateExpandGroupingSetsRule extends RelOptRule {
+
+ public static final DrillAggregateExpandGroupingSetsRule INSTANCE =
+ new DrillAggregateExpandGroupingSetsRule();
+ public static String GROUPING_ID_COLUMN_NAME = "$g";
+ public static String GROUP_ID_COLUMN_NAME = "$group_id";
+ public static String EXPRESSION_COLUMN_PLACEHOLDER = "EXPR$";
Review Comment:
Safer will be make them final:
```java
public static final String GROUPING_ID_COLUMN_NAME = "$g";
public static final String GROUP_ID_COLUMN_NAME = "$group_id";
public static final String EXPRESSION_COLUMN_PLACEHOLDER = "EXPR$";
```
> Add support of ROLLUP, CUBE, GROUPING SETS, GROUPING, GROUPING_ID, GROUP_ID
> support
> -----------------------------------------------------------------------------------
>
> Key: DRILL-3962
> URL: https://issues.apache.org/jira/browse/DRILL-3962
> Project: Apache Drill
> Issue Type: New Feature
> Reporter: Jinfeng Ni
> Assignee: Charles Givre
> Priority: Major
>
> These functions are important for BI analytical workload. Currently, Calcite
> supports those functions, but neither the planning or execution in Drill
> supports those functions.
> DRILL-3802 blocks those functions in Drill planning. But we should provide
> the support for those functions in both planning and execution of Drill.
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