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https://issues.apache.org/jira/browse/CALCITE-7925?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18141077#comment-18141077
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Stamatis Zampetakis commented on CALCITE-7925:
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This seems really close to CALCITE-7789. It seems that the request here is also
to conditionally disable simplifications on LIKE operator. Do we want to fully
override the behavior of simplifier or just turn off some simplifications?
> Proposal: Change RexSimplify::simplify* methods to "protected"
> --------------------------------------------------------------
>
> Key: CALCITE-7925
> URL: https://issues.apache.org/jira/browse/CALCITE-7925
> Project: Calcite
> Issue Type: Improvement
> Reporter: Steve Carlin
> Priority: Major
>
> I had to create a custom RexSimplify to deal with some difference that my
> database has with the way Calcite handles NULLs.
> This all works fine since I am able to inherit most of the behavior of
> RexSimplify with very small custom changes.
> I just came across a problem though. At this point, I'm not sure if it is a
> Calcite bug or if it's a behavior specific to my database. I'll mention the
> specifics at the end, but that's irrelevant to the purpose of this Jira.
> Whether it's a bug or not, I think overrides on simplifications should be
> allowed and the methods should be extensible/overrideable.
> I would like the ability to override specific implementation details on a
> specific operator. In my case, I'd like to override
> "simplifyLike(RexCall e, RexUnknownAs unknownAs)"
> But I cannot due this due to it being private. Can we change this to be
> "protected"?
> ---
> To be specific about the problem I'm hitting:
> In my LIKE clause, I have " s LIKE 'a\\%%' " My database treats the first
> four characters as the string "a" plus an escaped percentage sign. The
> fifth "%" character is treated as a wildcard.
> The simplifyLike behavior reduces all multiple wildcards into a single
> wildcard. So by "simplifying" the expression, I lose the wildcard character.
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