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https://issues.apache.org/jira/browse/CALCITE-2116?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16323523#comment-16323523
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Julian Hyde commented on CALCITE-2116:
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Are you talking about the scenario where a node A produces two output streams,
and sends the first stream to node B, another copy of the first stream to node
C, and the second stream to node D?
We cannot model that currently, even though there are scenarios where it would
be useful (e.g. an Insert sends rows to a table and also rows to modify an
index).
Note that the Spool operator (CALCITE-481) would be another way to create a DAG.
> The digests are not same for the common sub-expressions in HepPlanner
> ---------------------------------------------------------------------
>
> Key: CALCITE-2116
> URL: https://issues.apache.org/jira/browse/CALCITE-2116
> Project: Calcite
> Issue Type: Bug
> Affects Versions: 1.15.0
> Reporter: LeoWangLZ
> Assignee: Julian Hyde
> Fix For: 1.16.0
>
>
> The digests are not same for the same sub-query.
> like query
> {code:java}
> select * from (select * from dept union all select * from dept)a;
> {code}
> When run the query, The union relNode has two inputs, and it's same expectly
> and it's the same object instead of the print of plan, but Now they are not
> same.
> And for Test testReplaceCommonSubexpression, the rule is only firing once,
> but now it's two.
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