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https://issues.apache.org/jira/browse/FLINK-5520?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15830222#comment-15830222
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ASF GitHub Bot commented on FLINK-5520:
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Github user lincoln-lil commented on the issue:
https://github.com/apache/flink/pull/3141
@fhueske when I add more test cases for "outer joins" with local
predicates, I found different limitations between tableAPI and SQL, e.g.,
"SELECT c, g FROM Table3 left outer join Table5 on a = d AND e < 3" is valid,
but dsFromTuple3.leftOuterJoin(dsFromTuple5, 'a === 'd && 'e < 3) is invalid,
because validation in Join node sees original join predicates and validates
simply, while in DataSetJoinRule the join predicates could be pruned according
to the equivalence in relational algebra.
I have a question, should we keep the tableAPI consistent with SQL? If so,
the validation in tableAPI will be much more complex, and it reminds me the
previous discussion about validation either in one or two places. Or just
maintain the current implementation unchanged, because we will add support for
both FLINK-5498 and FLINK-5511 soon, then these differences will be eliminated.
What do you think ?
> Disable outer joins with non-equality predicates
> ------------------------------------------------
>
> Key: FLINK-5520
> URL: https://issues.apache.org/jira/browse/FLINK-5520
> Project: Flink
> Issue Type: Bug
> Components: Table API & SQL
> Affects Versions: 1.2.0
> Reporter: Fabian Hueske
> Assignee: lincoln.lee
> Priority: Blocker
> Fix For: 1.2.0
>
>
> Outer joins with non-equality predicates (and at least one equality
> predicate) compute incorrect results.
> Since this is not a very common requirement, I propose to disable this
> feature for the 1.2.0 release and correctly implement it for a later version.
> The fix should add checks in the Table API validation phase (to get a good
> error message) and in the DataSetJoinRule to prevent translation of SQL
> queries with non-equality predicates on outer joins.
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