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

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.20.0
• Component/s: core
• Labels: pull-request-available
• Assignee: Laurent Goujon
• Reporter: Laurent Goujon
• Created: 25/Jan/19 22:27
• Updated: 24/Jun/19 15:02
• Resolved: 22/May/19 17:24

Description

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

Issue Links

• relates to: CALCITE-2803 Identify expanded IS NOT DISTINCT FROM expression when pushing project past join
• links to: GitHub Pull Request #1226