[jira] [Comment Edited] (CALCITE-4094) Allow SqlUserDefinedFunction to define an optional Strong.Policy

["Ruben Q L (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-4094?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17148364#comment-17148364 ] 

Ruben Q L edited comment on CALCITE-4094 at 6/30/20, 7:55 AM:
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[~danny0405] the idea is having always the default policy {{Strong.Policy.AS_IS}} (so it will remain backwards compatible, the one who writes the udf does not need to specify it); but add mechanism (I guess another constructor in {{SqlUserDefinedFunction.java}}) so that we can specify a different policy value.


was (Author: rubenql):
[~danny0405] the idea is having always the default policy {{Strong.Policy.AS_IS}} (so it will remain backwards compatible, the one who writes the udf does not need to specify it); but add mechanism (I guess another constructor) so that we can specify a different policy value.

> Allow SqlUserDefinedFunction to define an optional Strong.Policy
> ----------------------------------------------------------------
>
>                 Key: CALCITE-4094
>                 URL: https://issues.apache.org/jira/browse/CALCITE-4094
>             Project: Calcite
>          Issue Type: Improvement
>          Components: core
>            Reporter: Ruben Q L
>            Assignee: Ruben Q L
>            Priority: Major
>
> {{FilterJoinRule}} performs some optimizations based on {{RelOptUitl#simplifyJoin}}. Specifically, this part of the code:
> {code}
> if (joinType.generatesNullsOnRight()
>   && Strong.isNotTrue(filter, rightBitmap)) {
>     joinType = joinType.cancelNullsOnRight();
> }
> {code}
> allows e.g. a LEFT join with a condition on its RHS to be transformed into an INNER join, with the condition pushed on its right input.
> In order to achieve this, the utility class {{Strong}} defines a certain {{Policy}} map, depending on the {{SqlKind}} of a {{RexNode}} (i.e. depending on the filter condition). In case of operators such as {{EQUALS}}, {{NOT_EQUALS}}, {{LESS_THAN}}, etc, it defines {{Policy.ANY}} (i.e. expression is null if and only if at least one of its arguments is null). In case of a left join with conditions with this policy on the right-hand-side, the join gets simplified by this module because of the nullability of the right columns. However, in the case of {{SqlUserDefinedFunction}} the policy is the default {{Policy.AS_IS}}, which prevents the simplification from happening.
> It is proposed to enrich {{SqlUserDefinedFunction}} with an optional {{Strong.Policy}}, and adapt {{Strong#isNull}} so that these functions can also benefit from this simplification.



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