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https://issues.apache.org/jira/browse/CALCITE-2973?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16807393#comment-16807393
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Lai Zhou commented on CALCITE-2973:
-----------------------------------
[~julianhyde] , consider another query that the join conditions contains an
equi condition and a non-equi condition meanwhile :
{code:java}
SELECT t1.i_item_desc FROM item t1 LEFT OUTER JOIN item_1 t2 ON
t1.i_item_sk=t2.i_item_sk and t2.i_item_sk <10000{code}
Merge join is also good for this query. But now it will be converted to a
nested loop join.
> 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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