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https://issues.apache.org/jira/browse/CALCITE-5285?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17605746#comment-17605746
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Krzysztof Ślusarski commented on CALCITE-5285:
----------------------------------------------
Yes, exactly. And this is done line by line in
CalcReduceExpressionsRule#onMatch (state before my PR):
{code:java}
call.transformTo(
calc.copy(calc.getTraitSet(), calc.getInput(), builder.getProgram()));
// New plan is absolutely better than old plan.
call.getPlanner().prune(calc); {code}
> CalcReduceExpressionsRule may transform to same rel
> ---------------------------------------------------
>
> Key: CALCITE-5285
> URL: https://issues.apache.org/jira/browse/CALCITE-5285
> Project: Calcite
> Issue Type: Bug
> Components: server
> Reporter: Krzysztof Ślusarski
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.33.0
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Method {{CalcReduceExpressionsRule#onMatch}} enters the branch and calculates
> {{reduceExpressions()}} condition. If that one is true it creates new calc.
> Unfortunately logic in {{reduceExpressions()}} is different then in the rest
> of the method and it can create a calc that is equal to the input.
> Example query {{{}SELECT floor(this / 1) FROM test{}}}.
> Input calc contains program with exprs:
> {{0 = \{RexInputRef@11348} "$0"}}
> {{1 = \{RexInputRef@11349} "$1"}}
> {{2 = \{RexCall@11350} "CAST($t1):BIGINT(32)"}}
> {{3 = \{RexLiteral@11351} "1:BIGINT(32)"}}
> {{4 = \{RexCall@11352} "/($t2, $t3)"}}
> {{5 = \{RexCall@11353} "FLOOR($t4)"}}
> The one on index 4 can be simplified (the division can be removed). That
> condition is met in {{{}reduceExpressions(){}}}, but following logic in
> {{onMatch()}} doesn't simplify that expression.
> This makes the output calc equals to input one which breaks the rest of query
> optimizing.
>
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