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https://issues.apache.org/jira/browse/HIVE-3562?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Phabricator updated HIVE-3562:
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Attachment: HIVE-3562.D5967.1.patch
navis requested code review of "HIVE-3562 [jira] Some limit can be pushed down
to map stage".
Reviewers: JIRA
DPAL-1910 Some limit can be pushed down to map stage
Queries with limit clause (with reasonable number), for example
select * from src order by key limit 10;
makes operator tree,
TS-SEL-RS-EXT-LIMIT-FS
But LIMIT can be partially calculated in RS, reducing size of shuffling.
TS-SEL-RS(TOP-N)-EXT-LIMIT-FS
TEST PLAN
EMPTY
REVISION DETAIL
https://reviews.facebook.net/D5967
AFFECTED FILES
common/src/java/org/apache/hadoop/hive/conf/HiveConf.java
ql/src/java/org/apache/hadoop/hive/ql/exec/ReduceSinkOperator.java
ql/src/java/org/apache/hadoop/hive/ql/optimizer/LimitPushdownOptimizer.java
ql/src/java/org/apache/hadoop/hive/ql/optimizer/Optimizer.java
ql/src/java/org/apache/hadoop/hive/ql/plan/ReduceSinkDesc.java
ql/src/test/queries/clientpositive/limit_pushdown.q
ql/src/test/results/clientpositive/limit_pushdown.q.out
MANAGE HERALD DIFFERENTIAL RULES
https://reviews.facebook.net/herald/view/differential/
WHY DID I GET THIS EMAIL?
https://reviews.facebook.net/herald/transcript/14199/
To: JIRA, navis
> Some limit can be pushed down to map stage
> ------------------------------------------
>
> Key: HIVE-3562
> URL: https://issues.apache.org/jira/browse/HIVE-3562
> Project: Hive
> Issue Type: Bug
> Reporter: Navis
> Assignee: Navis
> Priority: Trivial
> Attachments: HIVE-3562.D5967.1.patch
>
>
> Queries with limit clause (with reasonable number), for example
> {noformat}
> select * from src order by key limit 10;
> {noformat}
> makes operator tree,
> TS-SEL-RS-EXT-LIMIT-FS
> But LIMIT can be partially calculated in RS, reducing size of shuffling.
> TS-SEL-RS(TOP-N)-EXT-LIMIT-FS
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