[jira] [Created] (CALCITE-2807) Identify expanded IS NOT DISTINCT FROM expression when pushing down filter past join

["Laurent Goujon (JIRA)" <ji...@apache.org>]

Laurent Goujon created CALCITE-2807:
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             Summary: Identify expanded IS NOT DISTINCT FROM expression when pushing down filter past join
                 Key: CALCITE-2807
                 URL: https://issues.apache.org/jira/browse/CALCITE-2807
             Project: Calcite
          Issue Type: Improvement
          Components: core
            Reporter: Laurent Goujon
            Assignee: Julian Hyde


IS NOT DISTINCT FROM expressions in join condition might actually be considered as equi-join conditions, and RelOptUtil#splitJoinConditions() has support for it. But some other join related functions/rules don't.

One of them is RelOptUtil#pushDownJoinConditions (used by JoinPushExpressionsRule) which tries to push filter expressions below the join, but ends up modifying the join expression in a way which makes identify an IDNF condition impossible later.

For example expression OR(AND(IS_NULL($1), IS_NULL($4)), EQUALS($1,$4)) will be changed into OR(AND($3, $6), EQUALS($1, $5)) which makes it harder/impossible for RelOptUtil#splitJoinConditions() to identify an IS NOT DISTINCT FROM equi-join condition.

This is a variant of CALCITE-2803




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