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https://issues.apache.org/jira/browse/FLINK-7730?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16205613#comment-16205613
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ASF GitHub Bot commented on FLINK-7730:
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GitHub user xccui opened a pull request:
https://github.com/apache/flink/pull/4830
[FLINK-7730] [table] Restrict the predicates of table function left outer
join
## What is the purpose of the change
The PR aims to temporarily cover up the table function left outer join
problem by adding restrictions on the join predicates.
## Brief change log
- Predicates check for table function left outer join (correlate) are
added to `DataSetCalcRule` and `DataStreamCalcRule`.
- Update related tests.
- Refine the documents.
## Verifying this change
This change is already covered by existing tests, such as `CorrelateITCase`
and `CorrelateTest`.
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): (no)
- The public API, i.e., is any changed class annotated with
`@Public(Evolving)`: (no)
- The serializers: (no)
- The runtime per-record code paths (performance sensitive): (no)
- Anything that affects deployment or recovery: JobManager (and its
components), Checkpointing, Yarn/Mesos, ZooKeeper: (no)
## Documentation
- Does this pull request introduce a new feature? (no)
- If yes, how is the feature documented? (docs)
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/xccui/flink FLINK-7730
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/4830.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #4830
----
commit 58d2635877f76937cc23d97fe1aa1da8ff51ebd7
Author: Xingcan Cui <[email protected]>
Date: 2017-10-16T08:49:14Z
[FLINK-7730] [table] Add restrictions on table function left outer join
----
> TableFunction LEFT OUTER joins with ON predicates are broken
> ------------------------------------------------------------
>
> Key: FLINK-7730
> URL: https://issues.apache.org/jira/browse/FLINK-7730
> Project: Flink
> Issue Type: Bug
> Components: Table API & SQL
> Affects Versions: 1.4.0, 1.3.2
> Reporter: Fabian Hueske
> Assignee: Xingcan Cui
> Priority: Critical
>
> TableFunction left outer joins with predicates in the ON clause are broken.
> Apparently, the are no tests for this and it has never worked. I observed
> issues on several layers:
> - Table Function does not correctly validate equality predicate:
> {{leftOuterJoin(func1('c) as 'd, 'a.cast(Types.STRING) === 'd)}} is rejected
> because the predicate is not considered as an equality predicate (the cast
> needs to be pushed down).
> - Plans cannot be correctly translated: {{leftOuterJoin(func1('c) as 'd, 'c
> === 'd)}} gives an optimizer exception.
> - SQL queries get translated but produce incorrect results. For example
> {{SELECT a, b, c, d FROM MyTable LEFT OUTER JOIN LATERAL TABLE(tfunc(c)) AS
> T(d) ON d = c}} returns an empty result if the condition {{d = c}} never
> returns true. However, the outer side should be preserved and padded with
> nulls.
> So there seem to be many issues with table function outer joins. Especially,
> the wrong result produced by SQL queries need to be quickly fixed.
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