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https://issues.apache.org/jira/browse/CALCITE-4375?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17225787#comment-17225787
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Jiatao Tao commented on CALCITE-4375:
-------------------------------------
[~amaliujia]
Hash join is better than nestloop join, and after this change, filter can be
push down:
Hashjoin(emps.name = depts.name)
Filter(empno=1 or empno=2)
I think the benefits are great, by the way, we found many of this case in
TPC-DS.
> Merge join condition that has "OR" as much as possible
> ------------------------------------------------------
>
> Key: CALCITE-4375
> URL: https://issues.apache.org/jira/browse/CALCITE-4375
> Project: Calcite
> Issue Type: Bug
> Components: core
> Reporter: Jiatao Tao
> Assignee: Jiatao Tao
> Priority: Major
>
> SQL:
> SELECT * FROM emps,depts
> WHERE
> (emps.name = depts.name AND empno=1)
> OR
> (emps.name = depts.name AND empno=2)
>
> And the join after optimizer is:
> EnumerableNestedLoopJoin(condition=[OR(AND(=($1, $11), =($0, 1)), AND(=($1,
> $11), =($0, 2)))], joinType=[inner])
>
> In fact ($1, $11) can be extracted, and the join can be:
> HashJoin(condition=[AND(=($1, $11), OR(=($0, 1), =($0, 2)))],
> joinType=[inner])
>
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