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https://issues.apache.org/jira/browse/CALCITE-2838?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16766461#comment-16766461
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Julian Hyde commented on CALCITE-2838:
--------------------------------------
That sounds reasonable. Make sure that there aren't a lot of changes happening
for very little purpose, but otherwise I approve of this change.
> Simplification: Remove redundant IS TRUE checks
> -----------------------------------------------
>
> Key: CALCITE-2838
> URL: https://issues.apache.org/jira/browse/CALCITE-2838
> Project: Calcite
> Issue Type: Improvement
> Reporter: Zoltan Haindrich
> Assignee: Zoltan Haindrich
> Priority: Major
>
> In case simplifcation is already processing in unknownAsFalse mode, {{expr IS
> TRUE}} is redundant - and may just prevent further optimizations from
> happening:
> {code}
> @Test public void testRedundantIsTrue() {
> // in case of unknownAsFalse
> // x is TRUE <=> x
> checkSimplify3(isTrue(vBool(1)),
> "IS TRUE(?0.bool1)",
> "?0.bool1",
> "IS TRUE(?0.bool1)");
> }
> {code}
> there are some further possibilities
> {code}
> (unknownAsTrue) x is NOT FALSE <=> x
> (unknownAsTrue) x is FALSE <=> not x
> {code}
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