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https://issues.apache.org/jira/browse/FLINK-5520?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15827762#comment-15827762
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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 agree with you that the check in validation phase of the Table API
is useful for failing fast( IMO, it seems no difference on user experience that
when an exception be thrown either in validation or translation phase ?), but
there may be other rules can match and generate alternative plans to execute an
outer join. For instance, we internal implemented a HbaseTableSource extends
TableSource that can be joined as a TableSourceTable. We created a new rule
that is used to match inner and outer joins. Though such special tableSource
probably may not be suitable to be merged into Flink
master, in the future there could be other TableSourceTables which can
support different join predicates depending on their different physical storage
characteristics.
> 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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