Fabian Hueske created FLINK-7730:
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Summary: 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: 1.3.2, 1.4.0
Reporter: Fabian Hueske
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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