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https://issues.apache.org/jira/browse/CALCITE-2973?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16808174#comment-16808174
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Julian Hyde commented on CALCITE-2973:
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I agree with [~zabetak]. EnumerableMergeJoinRule should handle the cases that
can be implemented by EnumerableMergeJoin - no more, no less. If you enhance
EnumerableMergeJoin (say, adding a Rex condition to be evaluated whenever there
is a pair of rows that have matched) then you can enhance the rule to generate
code for it.
> Make EnumerableMergeJoinRule to support a theta join
> ----------------------------------------------------
>
> Key: CALCITE-2973
> URL: https://issues.apache.org/jira/browse/CALCITE-2973
> Project: Calcite
> Issue Type: New Feature
> Components: core
> Affects Versions: 1.19.0
> Reporter: Lai Zhou
> Priority: Minor
>
> Now the EnumerableMergeJoinRule only supports an inner and equi join.
> If users make a theta-join query for a large dataset (such as 10000*10000),
> the nested-loop join process will take dozens of time than the sort-merge
> join process .
> So if we can apply merge-join or hash-join rule for a theta join, it will
> improve the performance greatly.
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