[
https://issues.apache.org/jira/browse/HIVE-26524?focusedWorklogId=813666&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-813666
]
ASF GitHub Bot logged work on HIVE-26524:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 30/Sep/22 11:11
Start Date: 30/Sep/22 11:11
Worklog Time Spent: 10m
Work Description: zabetak commented on code in PR #3588:
URL: https://github.com/apache/hive/pull/3588#discussion_r984481438
##########
ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/rules/HiveRemoveEmptySingleRules.java:
##########
@@ -0,0 +1,280 @@
+/*
+ * 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.hadoop.hive.ql.optimizer.calcite.rules;
+
+import org.apache.calcite.plan.RelOptRule;
+import org.apache.calcite.plan.RelOptRuleCall;
+import org.apache.calcite.plan.RelOptUtil;
+import org.apache.calcite.plan.RelRule;
+import org.apache.calcite.plan.hep.HepRelVertex;
+import org.apache.calcite.plan.volcano.RelSubset;
+import org.apache.calcite.rel.RelNode;
+import org.apache.calcite.rel.core.Aggregate;
+import org.apache.calcite.rel.core.Filter;
+import org.apache.calcite.rel.core.Join;
+import org.apache.calcite.rel.core.JoinRelType;
+import org.apache.calcite.rel.core.Project;
+import org.apache.calcite.rel.core.Sort;
+import org.apache.calcite.rel.core.Union;
+import org.apache.calcite.rel.core.Values;
+import org.apache.calcite.rel.rules.PruneEmptyRules;
+import org.apache.calcite.rex.RexNode;
+import org.apache.calcite.tools.RelBuilder;
+import org.apache.hadoop.hive.ql.optimizer.calcite.Bug;
+import org.apache.hadoop.hive.ql.optimizer.calcite.HiveRelFactories;
+
+import java.util.Collections;
+import java.util.List;
+
+import static com.google.common.collect.Iterables.concat;
+
+/**
+ * This class provides access to Calcite's {@link PruneEmptyRules}.
+ * The instances of the rules use {@link
org.apache.hadoop.hive.ql.optimizer.calcite.HiveRelBuilder}.
+ */
+public class HiveRemoveEmptySingleRules extends PruneEmptyRules {
+
+ public static final RelOptRule PROJECT_INSTANCE =
+ RelRule.Config.EMPTY
+ .withDescription("HivePruneEmptyProject")
+ .as(PruneEmptyRules.RemoveEmptySingleRule.Config.class)
+ .withOperandFor(Project.class, project -> true)
Review Comment:
One thing to keep in mind is that the rule may turn `ConventionXx` to
`HiveXX` since we use the `HIVE_BUILDER`. If you think that it is safe to do so
here then I am fine with it.
Issue Time Tracking
-------------------
Worklog Id: (was: 813666)
Time Spent: 5h 10m (was: 5h)
> Use Calcite to remove sections of a query plan known never produces rows
> ------------------------------------------------------------------------
>
> Key: HIVE-26524
> URL: https://issues.apache.org/jira/browse/HIVE-26524
> Project: Hive
> Issue Type: Improvement
> Components: CBO
> Reporter: Krisztian Kasa
> Assignee: Krisztian Kasa
> Priority: Major
> Labels: pull-request-available
> Time Spent: 5h 10m
> Remaining Estimate: 0h
>
> Calcite has a set of rules to remove sections of a query plan known never
> produces any rows. In some cases the whole plan can be removed. Such plans
> are represented with a single {{Values}} operators with no tuples. ex.:
> {code:java}
> select y + 1 from (select a1 y, b1 z from t1 where b1 > 10) q WHERE 1=0
> {code}
> {code:java}
> HiveValues(tuples=[[]])
> {code}
> Other cases when plan has outer join or set operators some branches can be
> replaced with empty values moving forward in some cases the join/set operator
> can be removed
> {code:java}
> select a2, b2 from t2 where 1=0
> union
> select a1, b1 from t1
> {code}
> {code:java}
> HiveAggregate(group=[{0, 1}])
> HiveTableScan(table=[[default, t1]], table:alias=[t1])
> {code}
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