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https://issues.apache.org/jira/browse/CALCITE-935?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14972839#comment-14972839
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Julian Hyde commented on CALCITE-935:
-------------------------------------
I reviewed your changes. I tidied up by gathering the code into a method, and
using a multimap to defer detecting duplicates. I also added a test case. The
test case shows that if you have a non-equi constraint, say 'mgr is null' then
it prevents any constant reduction occurring. That is not OK. Constraints which
are not 'column = constant' (and that includes constraints 'column = constant1
and column = constant2') should be ignored, but they should not prevent
constant reduction.
Can you build on the work in
https://github.com/julianhyde/incubator-calcite/tree/935-reduce-multiple-constraints
and make sure that testReduceConstantsDup2 reduces empno to 10 and ignores the
constraints on deptno and mgr. (If you reduce mgr to null I wouldn't object.)
> Improve ReduceExpressionRule to deal with multiple "equals to literal" in
> predicate
> -----------------------------------------------------------------------------------
>
> Key: CALCITE-935
> URL: https://issues.apache.org/jira/browse/CALCITE-935
> Project: Calcite
> Issue Type: Bug
> Reporter: Pengcheng Xiong
> Assignee: Julian Hyde
> Attachments: CALCITE-935.01.patch
>
>
> In ReduceExpressionRule.java,
> L396-397:
> final ImmutableMap<RexNode, RexLiteral> constants =
> predicateConstants(predicates);
> The query is "select * from src where (key='12' and key is
> null);" Here 'key' is a string type and it is one of the columns of 'src'
> table.
> Then we will have predicates [=($0, '12'), isnull($0)], which is the input of
> the
> predicateConstants, and the function will return "{$0='12'}"
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