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https://issues.apache.org/jira/browse/CALCITE-254?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Julian Hyde updated CALCITE-254:
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Summary: Propagate RelCollation on aliased columns in JoinRule (was:
Propagate RelCollation on aliased columns in JoinRule.)
> Propagate RelCollation on aliased columns in JoinRule
> -----------------------------------------------------
>
> Key: CALCITE-254
> URL: https://issues.apache.org/jira/browse/CALCITE-254
> Project: Calcite
> Issue Type: Bug
> Reporter: GitHub Import
> Labels: github-import
>
> Consider this query:
> SELECT *
> FROM emp JOIN dept ON emp.deptno = dept.deptno
> ORDER BY dept.deptno;
> If table emp is sorted on emp.deptno (for example, table emp has index on
> emp.deptno, or table emp comes from a subquery which sorts on emp.deptno),
> the join predicate emp.deptno = dept.deptno indicates the two columns are
> aliased columns in terms of ordering. If JoinRule keep track of the
> RelCollation trait for the aliased columns, the query essentially become as
> following
> SELECT *
> FROM emp JOIN dept ON emp.deptno = dept.deptno
> ORDER BY emp.deptno;
> The ORDER BY should not require a SortRel, since the input table emp is
> sorted on emp.depno.
> Currently, optiq framework does not recognize the aliased columns from join =
> predicates, and may introduce redundant sort to the plan.
> This issue is relevant to issue
> ([#41|https://github.com/JulianHyde/optiq/issues/41] |
> [CALCITE-41|https://issues.apache.org/jira/browse/CALCITE-41])
> https://github.com/julianhyde/optiq/issues/41
> ---------------- Imported from GitHub ----------------
> Url: https://github.com/julianhyde/optiq/issues/254
> Created by: [jinfengni|https://github.com/jinfengni]
> Labels:
> Created at: Thu Apr 17 22:53:46 CEST 2014
> State: open
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