[jira] [Comment Edited] (CALCITE-5032) The unexpected behavior on method RelOptUtil#splitJoinCondition

["Benchao Li (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-5032?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17501698#comment-17501698 ] 

Benchao Li edited comment on CALCITE-5032 at 3/6/22, 1:02 PM:
--------------------------------------------------------------

Hi [~luoyuxia] ,
I think you raised a valid question, the result for you case is not correct IMO.
 
For your case, I think there are two ways to handle it:
1. we require the condition to be simplified before call splitJoinCondition in the doc,
2. we fix it like you said: set the rightInput correctly.


was (Author: libenchao):
Hi [~luoyuxia] ,
I think you raised a valid question, the result for you case is not correct IMO.
 
For your case, I think there are two ways to handle it:
1. we require the condition to be simplified before call splitJoinCondition in the doc,
2. we fix it like you said: set the rightInput correctly.
 
However, I'm further confused about this part:
{code:java}
if ((rangeOp == null)
    && ((leftKey == null) || (rightKey == null))) {
    // ...
} {code}
If we push this expr down into projection, the semantic of Join may be not correct, for example, `LEFT JOIN`.

> The unexpected behavior on method RelOptUtil#splitJoinCondition
> ---------------------------------------------------------------
>
>                 Key: CALCITE-5032
>                 URL: https://issues.apache.org/jira/browse/CALCITE-5032
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>            Reporter: luoyuxia
>            Priority: Major
>
> When I call the method 
> {code:java}
> RexNode splitJoinCondition(
>       List<RelDataTypeField> sysFieldList,
>       List<RelNode> inputs,
>       RexNode condition,
>       List<List<RexNode>> joinKeys,
>       @Nullable List<Integer> filterNulls,
>       @Nullable List<SqlOperator> rangeOp)
> {code}
> , and the passed `joinKeys` is  list with size 2, `condition` is like "1 = 1",  then I found the `joinKeys` passed dosen't change as expected. 
> For the `joinKeys`,  the first list will contain two RexNodes, and the second list contains no RexNode. I think the expected behavior should be the first list contain one RexNode, and the second contain one RexNode too.
> After I dive into the code, I found such code will be invoked:
> {code:java}
> if ((rangeOp == null)
>           && ((leftKey == null) || (rightKey == null))) {
>         // no equality join keys found yet:
>         // try transforming the condition to
>         // equality "join" conditions, e.g.
>         //     f(LHS) > 0 ===> ( f(LHS) > 0 ) = TRUE,
>         // and make the RHS produce TRUE, but only if we're strictly
>         // looking for equi-joins
>         final ImmutableBitSet projRefs = InputFinder.bits(condition);
>         leftKey = null;
>         rightKey = null;
>         boolean foundInput = false;
>         for (int i = 0; i < inputs.size() && !foundInput; i++) {
>           if (inputsRange[i].contains(projRefs)) {
>             leftInput = i;
>             leftFields = inputs.get(leftInput).getRowType().getFieldList();
>             leftKey = condition.accept(
>                 new RelOptUtil.RexInputConverter(
>                     rexBuilder,
>                     leftFields,
>                     leftFields,
>                     adjustments));
>             rightKey = rexBuilder.makeLiteral(true);
>             // effectively performing an equality comparison
>             kind = SqlKind.EQUALS;
>             foundInput = true;
>           }
>         }
>       }
> {code}
> It'll set `leftKey` and `righeKey`,  but it won't set `rightInput`. So `rightInput` will be 0.
> Then it'll try to add `leftKey` and `righeKey` to `joinKeys`,
> {code:java}
> addJoinKey(
>             joinKeys.get(leftInput),
>             leftKey,
>             (rangeOp != null) && !rangeOp.isEmpty());
> addJoinKey(
>             joinKeys.get(rightInput),
>             rightKey,
> (rangeOp != null) && !rangeOp.isEmpty());
> {code}
> But the `rightInput` is 0, so the first list of `joinKeys`  will be also add `righeKey`.
> Could anyone please help me? Is it a bug or I misunderstand something? Thanks very much.



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