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https://issues.apache.org/jira/browse/HIVE-948?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13577674#comment-13577674
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Phabricator commented on HIVE-948:
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ashutoshc has requested changes to the revision "HIVE-948 [jira] more query
plan optimization rules".
Mostly looks good. Have couple more comments. But I do think we need to name
it better than CleanupProcessor.
INLINE COMMENTS
ql/src/java/org/apache/hadoop/hive/ql/optimizer/CleanupProcessor.java:47
CleanupProcessor is not indicative of kind of optimization its doing. Its not
descriptive enough. NonBlockingOpDeDupProc may not be an optimal choice. But we
do need better than CleanupProcessor.
ql/src/java/org/apache/hadoop/hive/ql/optimizer/CleanupProcessor.java:83 What
if parent isSelectStar and child is not? Shouldn't the surviving operator
(parent) should be selectStar if either parent or child is.
ql/src/java/org/apache/hadoop/hive/ql/ppd/PredicateTransitivePropagate.java:75
Per Namit's comment here:
https://reviews.facebook.net/D5325?id=26877#inline-39651 RS->MJ is not allowed
anymore. So, we should get rid of second predicate of this OR rule here.
REVISION DETAIL
https://reviews.facebook.net/D8463
BRANCH
DPAL-1980
ARCANIST PROJECT
hive
To: JIRA, ashutoshc, navis
> more query plan optimization rules
> -----------------------------------
>
> Key: HIVE-948
> URL: https://issues.apache.org/jira/browse/HIVE-948
> Project: Hive
> Issue Type: Improvement
> Reporter: Ning Zhang
> Assignee: Navis
> Attachments: HIVE-948.D8463.1.patch, HIVE-948.D8463.2.patch
>
>
> Many query plans are not optimal in that they contain redundant operators.
> Some examples are unnecessary select operators (select followed by select,
> select output being the same as input etc.). Even though these operators are
> not very expensive, they could account for around 10% of CPU time in some
> simple queries. It seems they are low-hanging fruits that we should pick
> first.
> BTW, it seems these optimization rules should be added at the last stage of
> the physical optimization phase since some redundant operators are added to
> facilitate physical plan generation.
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