[
https://issues.apache.org/jira/browse/HIVE-2337?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13078551#comment-13078551
]
jirapos...@reviews.apache.org commented on HIVE-2337:
-----------------------------------------------------
-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/1275/
-----------------------------------------------------------
Review request for hive.
Summary
-------
Initial patch
This addresses bug HIVE-2337.
https://issues.apache.org/jira/browse/HIVE-2337
Diffs
-----
http://svn.apache.org/repos/asf/hive/trunk/ql/src/java/org/apache/hadoop/hive/ql/ppd/OpProcFactory.java
1153293
Diff: https://reviews.apache.org/r/1275/diff
Testing
-------
Thanks,
Charles
> Predicate pushdown erroneously conservative with outer joins
> ------------------------------------------------------------
>
> Key: HIVE-2337
> URL: https://issues.apache.org/jira/browse/HIVE-2337
> Project: Hive
> Issue Type: Bug
> Components: Query Processor
> Reporter: Charles Chen
> Assignee: Charles Chen
> Attachments: HIVE-2337v1.patch
>
>
> The predicate pushdown filter is not applying left associativity of joins
> correctly in determining possible aliases for pushing predicates.
> In hive.ql.ppd.OpProcFactory.JoinPPD.getQualifiedAliases, the criteria for
> pushing aliases is specified as:
> {noformat}
> /**
> * Figures out the aliases for whom it is safe to push predicates based on
> * ANSI SQL semantics For inner join, all predicates for all aliases can
> be
> * pushed For full outer join, none of the predicates can be pushed as
> that
> * would limit the number of rows for join For left outer join, all the
> * predicates on the left side aliases can be pushed up For right outer
> * join, all the predicates on the right side aliases can be pushed up
> Joins
> * chain containing both left and right outer joins are treated as full
> * outer join. [...]
> *
> * @param op
> * Join Operator
> * @param rr
> * Row resolver
> * @return set of qualified aliases
> */
> {noformat}
> Since hive joins are left associative, something like "a RIGHT OUTER JOIN b
> LEFT OUTER JOIN c INNER JOIN d" should be interpreted as "((a RIGHT OUTER
> JOIN b) LEFT OUTER JOIN c) INNER JOIN d", so there would be cases where joins
> with both left and right outer joins can have aliases that can be pushed.
> Here, aliases a and d are eligible to be pushed up while the current criteria
> provide that none are eligible.
--
This message is automatically generated by JIRA.
For more information on JIRA, see: http://www.atlassian.com/software/jira
