Details
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Improvement
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Status: Closed
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Major
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Resolution: Fixed
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None
Description
FilterJoinRule performs some optimizations based on RelOptUtil#simplifyJoin. Specifically, this part of the code:
if (joinType.generatesNullsOnRight()
&& Strong.isNotTrue(filter, rightBitmap)) {
joinType = joinType.cancelNullsOnRight();
}
allows e.g. a LEFT join with a condition on its RHS to be transformed into an INNER join, with the condition pushed on its right input.
In order to achieve this, the utility class Strong defines a certain Policy map, depending on the SqlKind of a RexNode (i.e. depending on the filter condition). In case of operators such as EQUALS, NOT_EQUALS, LESS_THAN, etc, it defines Policy.ANY (i.e. expression is null if and only if at least one of its arguments is null). In case of a left join with conditions with this policy on the right-hand-side, the join gets simplified by this module because of the nullability of the right columns. However, in the case of SqlUserDefinedFunction the policy is the default Policy.AS_IS, which prevents the simplification from happening.
It is proposed to enrich SqlUserDefinedFunction with an optional Strong.Policy, and adapt Strong code so that these functions can also benefit from this simplification.
Attachments
Issue Links
- relates to
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CALCITE-4099 Unify Strong.Policy and NullPolicy
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- Open
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- links to
