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https://issues.apache.org/jira/browse/IMPALA-9162?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Aman Sinha resolved IMPALA-9162.
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Fix Version/s: Impala 3.4.0
Resolution: Fixed
> Incorrect redundant predicate applied to outer join
> ---------------------------------------------------
>
> Key: IMPALA-9162
> URL: https://issues.apache.org/jira/browse/IMPALA-9162
> Project: IMPALA
> Issue Type: Bug
> Components: Frontend
> Reporter: Aman Sinha
> Assignee: Aman Sinha
> Priority: Major
> Fix For: Impala 3.4.0
>
> Attachments: create.sql.txt
>
>
> Run the attached create.sql script to create the tables and view. The
> following query shows an incorrect redundant predicate applied to the outer
> join. This seems another variant of past issues such as IMPALA-7957 and
> IMPALA-8386.
> {noformat}
> // Has a redundant predicate as 'Other predicates' on Outer Join
> Query: explain select x.* from (select v1.c3, v1.max_c3 from v.t2 left join
> v.v1 on t2.c2=v1.c3) as x
>
>
> 06:HASH JOIN [RIGHT OUTER JOIN, PARTITIONED]
> hash predicates: c3 = t2.c2
> other predicates: c3 = max(c3) . <-- WRONG
> runtime filters: RF000 <- t2.c2
> row-size=20B cardinality=397
>
> --13:EXCHANGE [HASH(t2.c2)]
>
> 00:SCAN HDFS [v.t2]
> HDFS partitions=1/1 files=1 size=639B
> row-size=4B cardinality=397
>
>
> 12:EXCHANGE [HASH(c3)]
>
>
>
> 05:HASH JOIN [INNER JOIN, BROADCAST]
>
> hash predicates: c3 = max(c3)
>
> runtime filters: RF002 <- max(c3)
>
> row-size=16B cardinality=207
> {noformat}
>
> By comparison, the following query which does not have the v1.max_c3 column
> in the SELECT list produces the correct plan:
> {noformat}
> // Does not have the redundant predicate
> Query: explain select x.* from (select v1.c3 from v.t2 left join v.v1 on
> t2.c2=v1.c3) as x
> 06:HASH JOIN [RIGHT OUTER JOIN, PARTITIONED]
> hash predicates: c3 = t2.c2
> runtime filters: RF000 <- t2.c2
> row-size=20B cardinality=397
> --13:EXCHANGE [HASH(t2.c2)]
> 00:SCAN HDFS [v.t2]
> HDFS partitions=1/1 files=1 size=639B
> row-size=4B cardinality=397
> 12:EXCHANGE [HASH(c3)]
> 05:HASH JOIN [INNER JOIN, BROADCAST]
> hash predicates: c3 = max(c3)
> runtime filters: RF002 <- max(c3)
> row-size=16B cardinality=207
> {noformat}
> Due the redundant predicate, the first query produces wrong results.
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