[jira] [Commented] (CALCITE-2997) Avoid pushing down join condition in SqlToRelConverter

["Steven Talbot (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-2997?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17106592#comment-17106592 ] 

Steven Talbot commented on CALCITE-2997:
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cc [~julianhyde]

I'd move to reopen this. Even if the original case perhaps does not need to turn this off, I think there are valid cases where we would want to add a config parameter to disable this behavior. While the push down provides a more optimized plan, it also creates a more complex tree of RelNodes and writes much more verbose SQL if those RelNodes are translated back to SQL with the Projects that this rule creates. I could see a variety of cases where one would prefer for those reasons to disable this behavior.

> Avoid pushing down join condition in SqlToRelConverter
> ------------------------------------------------------
>
>                 Key: CALCITE-2997
>                 URL: https://issues.apache.org/jira/browse/CALCITE-2997
>             Project: Calcite
>          Issue Type: Bug
>            Reporter: Jin Xing
>            Priority: Major
>
> In current code, *SqlToRelConverter:createJoin* is calling *RelOptUtil.pushDownJoinConditions* for optimization. And we can find below conversion from *SqlNode* to *RelNode*:
> {code:java}
> SqlNode:
> select * from A join B on A.x = B.x * 2
> RelNode (Logical-Plan):
> Join (condition:col0=col1)
> |-Project(x as col0)
> | |-Scan(A)
> |-Project(x * 2 as col1)
>   |-Scan(B){code}
> As we can see the logical plan(*RelNode*) posted above is not the pure reflection of the original SQL String(*SqlNode*). The optimization is mixed into the phase on which AST is converted to Logical-Plan. Actually optimizing rule of JoinPushExpressionsRule is doing exactly the same kind of thing. Shall we just keep the optimization inside Optimized-Logical-Plan ? I mean shall we avoid calling *RelOptUtil.pushDownJoinConditions* in *SqlToRelConverter:createJoin*
> I raised this issue because that we are doing something based on the Logical-Plan. And it makes us really confused that the Logical-Plan doesn't corresponds to SqlNode. 
>  
>  



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