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https://issues.apache.org/jira/browse/CALCITE-935?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14973558#comment-14973558
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Pengcheng Xiong commented on CALCITE-935:
-----------------------------------------
Hi Julian, Thanks for your efforts. I thought about the multi map for a while
and I changed it back to basic map due to 2 reasons (1) as RexLiteral is
immutable too, a constant '10' is different from a constant '10'. Thus there
will be two values of '10'. (2) We only need a single literal value. Storing
multiple values in a multi-map is not that useful. The new patch is in
https://github.com/julianhyde/incubator-calcite/commit/ee02796a4f7a1c26f040657bb58026fa03da8666
and I already sent u a pull request. Plz let me know what you think. Thanks.
> Improve how ReduceExpressionsRule handles duplicate constraints
> ---------------------------------------------------------------
>
> Key: CALCITE-935
> URL: https://issues.apache.org/jira/browse/CALCITE-935
> Project: Calcite
> Issue Type: Bug
> Reporter: Pengcheng Xiong
> Assignee: Pengcheng Xiong
> Fix For: 1.5.0
>
> Attachments: CALCITE-935.01.patch
>
>
> We need to improve ReduceExpressionRule to deal with multiple "equals to
> literal" in predicate. In ReduceExpressionRule.java, L396-397:
> {code}final ImmutableMap<RexNode, RexLiteral> constants =
> predicateConstants(predicates);{code}
> The query is {code}select * from src where (key='12' and key is null);{code}
> Here 'key' is a string type and it is one of the columns of 'src' table.
> Then we will have predicates {noformat}[=($0, '12'),
> isnull($0)]{noformat}which is the input of the
> predicateConstants, and the function will return "{$0='12'}"
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