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https://issues.apache.org/jira/browse/CALCITE-4681?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17376451#comment-17376451
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ZiLin Chen commented on CALCITE-4681:
-------------------------------------
I had tried the way using predicate restricting only empty collation or any
distribution RelSubset, But XXX operand can be Sort, which has collation. I can
not determine which collation the XXX should have at the beginning. So using
predicate way is not a general solution. I also had tried add some logic in
matches. But matches may check fail after DeferringRuleCall in some case.
(RelSet has been merged). All these ways can't work really well, because I even
don't care about what XXX is and don't want to match it. Matching will cause
performance problem when the number of RelSubset become large.
{code:java}
public boolean matches(RelOptRuleCall call) {
return ( (LogicalJoin)call.rel(0)).getLeft() == call.rel(1);
}
{code}
> Rule operand match specific shape with or without
> RelSubset.class/RelNode.class
> -------------------------------------------------------------------------------
>
> Key: CALCITE-4681
> URL: https://issues.apache.org/jira/browse/CALCITE-4681
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Reporter: ZiLin Chen
> Priority: Major
>
> If we want to match such a pattern, LogicalJoin1 with left Input XXX(original
> LogicalJoin1 left input) and with right input (LogicalJoin.class). we wound
> find that XXX we should use RelNode.class or RelSubset.class. However both
> RelNode.class and RelSubset.class will match all kind of traitSet which is
> inefficient（rule may fires multi time just because of some kind of XXX with
> different trait）, especially when this is a JoinReorder Rule.
> The XXX operand we want to match is exact what LogicalJoin1.getLeft() return.
> LogicalJoin1
> - XXX(original LogicalJoin1 left input)
> - LogicalJoin2
>
> Is that any way we can provide to solve this problem?
> One way maybe changing what RelSubset.class operand match meaning? (Now,
> there is no rule in calcite with RelSubset.class as match operand. Before
> JoinAssociateRule is the only one match RelSubset.class, but change later )
>
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