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https://issues.apache.org/jira/browse/CALCITE-2454?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16740063#comment-16740063
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Vladimir Sitnikov commented on CALCITE-2454:
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[~julianhyde],
1) The test does fail without the fix
2) VolcanoPlanner uses {{Pair.of(newDigest, rel.getRowType())}} for
{{mapDigestToRel}}. It was added in
https://gitbox.apache.org/repos/asf?p=calcite.git;a=commit;h=e5b0d9d68b802f12aeaaef32ce7ef6a274a2ebda
with comment of
{quote} one ProjectRel had an INTEGER null literal and another had a VARCHAR
null literal{quote}
I wonder if we should just add data type to the RexLiteral digest instead?
Alternative option is to use {{Pair.of<digest, type>}} keys in planner, and
make javadoc for {{org.apache.calcite.plan.RelOptNode#getDigest}} clear that it
should not include rowtype since rowtype is an implicit part of the digest. If
so, we would want to remove rowtype from Values#digest
Any thoughts?
> HepPlanner should not pick cached RelNode when type mismatch while digest
> matches
> ---------------------------------------------------------------------------------
>
> Key: CALCITE-2454
> URL: https://issues.apache.org/jira/browse/CALCITE-2454
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.17.0
> Reporter: Yuzhao Chen
> Assignee: Julian Hyde
> Priority: Major
> Labels: pull-request-available
>
> After CALCITE-2116, a RelNode will be reused based on digest, but now many
> nodes's digests do not have type info, e.g. LogicalProject, this will affect
> some rules when we wanna transform to a node with same digest and same type
> (HepPlanner may pick out a RelNode with different type).
> So, we should add type info just like VolcanoPlanner.
> We encounter this problem with plan like below:
> {code:java}
> Union
> +-- project1(a: int, b:int, c: double)
> | +-- project2(a: bigint: b: int, c:double)
> +-- project3
> {code}
> We wanna cast a from bigint -> int so we can have a union with project1 and
> project3, but with ProjectMergeRule, while merging project1 and project2,
> HepPlanner will think project2 and project1 are identical and it gives back
> project2. But actually we wanna pick project1.
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