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https://issues.apache.org/jira/browse/CALCITE-2326?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16633448#comment-16633448
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Julian Hyde commented on CALCITE-2326:
--------------------------------------
I have done the re-factoring in
https://github.com/julianhyde/calcite/tree/2326-simplify-unknown-as. It is
several messy commits right now, but the key changes are there:
* Add enum RexUnknownAs with values TRUE, FALSE, UNKNOWN. UNKNOWN means "as
is", FALSE is the previous unknownAsFalse behavior, and TRUE is new.
* In {{RexSimplify}} add an {{unknownAs}} argument to {{simplify}},
{{simplifyAnd}} and {{simplifyAnds}}, {{simplifyFilterPredicates}} methods. The
previous methods are deprecated.
* Deprecate the {{RexSimplify}} constructor that passes {{unknownAsFalse}}, but
if people use it, it still works. The value of the {{unknownAsFalse}} becomes a
field that is the default value for the {{unknownAs}} parameter to the
deprecated {{simplify}}, {{simplifyAnd}}, {{simplifyAnds}},
{{simplifyFilterPredicates}} methods that do not have an {{unknownAs}}
parameter.
* Add test helper method {{checkSimplify3}} that checks simplification for
unknownAs UNKNOWN, FALSE, TRUE. {{checkSimplify2}} calls it, assuming that the
result for TRUE is the same as UNKNOWN.
[~vlsi], [~kgyrtkirk], [~jcamachorodriguez], Can you please review? It is not
perfect, but it is progress. I am prepared to make cleanups and accept
constructive criticism but I will be extremely dismayed if this change receives
a -1.
> Generalize p(x) IS TRUE/FALSE/UNKNOWN handling in RexSimplify
> -------------------------------------------------------------
>
> Key: CALCITE-2326
> URL: https://issues.apache.org/jira/browse/CALCITE-2326
> Project: Calcite
> Issue Type: Improvement
> Reporter: Zoltan Haindrich
> Assignee: Zoltan Haindrich
> Priority: Major
>
> Currently only IS TRUE is handle by the unknownAsFalse field variable.
> The main goal would be to extend the logic to also handle IS FALSE cases (and
> possibly IS UNKNOWN too)
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