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https://issues.apache.org/jira/browse/HIVE-18008?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16246823#comment-16246823
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Sergey Shelukhin commented on HIVE-18008:
-----------------------------------------
Appears to have broken the build:
{noformat}
[ERROR] Failed to execute goal
org.apache.maven.plugins:maven-compiler-plugin:3.6.1:compile (default-compile)
on project hive-exec: Compilation failure
[ERROR]
/Users/sergey/git/hivegit/ql/src/java/org/apache/hadoop/hive/ql/parse/CalcitePlanner.java:[208,57]
cannot find symbol
[ERROR] symbol: class HiveRemoveGBYSemiJoinRule
[ERROR] location: package org.apache.hadoop.hive.ql.optimizer.calcite.rules
[ERROR] -> [Help 1]
{noformat}
> Add optimization rule to remove gby from right side of left semi-join
> ---------------------------------------------------------------------
>
> Key: HIVE-18008
> URL: https://issues.apache.org/jira/browse/HIVE-18008
> Project: Hive
> Issue Type: Improvement
> Components: Query Planning
> Reporter: Vineet Garg
> Assignee: Vineet Garg
> Attachments: HIVE-18008.1.patch, HIVE-18008.2.patch
>
>
> Group by (on same keys as semi join) as right side of Left semi join is
> unnecessary and could be removed. We see this pattern in subqueries with
> explicit distinct keyword e.g.
> {code:sql}
> explain select * from src b where b.key in (select distinct key from src a
> where a.value = b.value)
> {code}
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