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https://issues.apache.org/jira/browse/HIVE-948?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13575404#comment-13575404
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Phabricator commented on HIVE-948:
----------------------------------
ashutoshc has requested changes to the revision "HIVE-948 [jira] more query
plan optimization rules".
Some comments.
INLINE COMMENTS
ql/src/java/org/apache/hadoop/hive/ql/optimizer/CleanupProcessor.java:47 I
think better name for this class could be NonBlockingOpDeDupProc ?
ql/src/java/org/apache/hadoop/hive/ql/optimizer/CleanupProcessor.java:91 It
doesn't look like terminal is used. This should be removed.
ql/src/java/org/apache/hadoop/hive/ql/optimizer/CleanupProcessor.java:101
Would also like to add cFil = null here?
ql/src/java/org/apache/hadoop/hive/ql/optimizer/CleanupProcessor.java:78
looks like to be safe we should also add cSel = null here.
ql/src/java/org/apache/hadoop/hive/ql/optimizer/CleanupProcessor.java:88 It
will be good to add comment why in case of sampling predicate we dont attempt
to merge filters.
ql/src/java/org/apache/hadoop/hive/ql/optimizer/CleanupProcessor.java:75 Do
you also want to add : pSEL.getConf().setSelectStar
(pSel.getConf().isSelectStar() || cSEL.getConf().isSelectStar);
And similarly for selStarNoCompute ?
ql/src/java/org/apache/hadoop/hive/ql/optimizer/CleanupProcessor.java:98 Do
you also want to add
pFIL.getConf().setSortedFilter(pFIL.getConf().getSortedFilter() ||
cFIL.getConf().getSortedFilter()); ?
ql/src/java/org/apache/hadoop/hive/ql/ppd/PredicateTransitivePropagate.java:76
RS -> MJ is disallowed after HIVE-3784, so this part of this rule can be
removed.
ql/src/java/org/apache/hadoop/hive/ql/ppd/PredicateTransitivePropagate.java:66
Add annotation @Override
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
>
>
> 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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