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https://issues.apache.org/jira/browse/CALCITE-1505?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15688791#comment-15688791
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Julian Hyde commented on CALCITE-1505:
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I'm not sure, but I suspect that it's because constant reduction is expensive
or because it requires the user to specify a {{RelOptPlanner.Executor}}. Try
changing the {{false}} to {{true}} and see whether anything breaks in the test
suite (or if the test suite gets noticeably slower).
I see that {{CalcitePrepareImpl.CONSTANT_REDUCTION_RULES}} is private, and
that's a shame. It would probably be useful if constant reduction was packaged
up as a program (in {{Programs}}, say) so that people rolling their own planner
could do constant reduction as an early and a late phase in planning.
Powerful ingredients like constant reduction are best used sparingly.
> Enable constant reduction rules
> -------------------------------
>
> Key: CALCITE-1505
> URL: https://issues.apache.org/jira/browse/CALCITE-1505
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Reporter: Andreas Damm
> Assignee: Julian Hyde
> Priority: Minor
>
> In CalcitePrepareImpl.createPlanner/3 the constant reduction rules are always
> disabled ("if (false) ...") with a comment stating "Change the below to
> enable constant-reduction". Are these rules working? Why are they excluded?
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