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https://issues.apache.org/jira/browse/CALCITE-3256?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated CALCITE-3256:
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Labels: pull-request-available (was: )
> Add ProjectOnProjectToProjectUnifyRule for materialization matching.
> --------------------------------------------------------------------
>
> Key: CALCITE-3256
> URL: https://issues.apache.org/jira/browse/CALCITE-3256
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Reporter: jin xing
> Assignee: jin xing
> Priority: Minor
> Labels: pull-request-available
>
> In current implementation of rules in SubstitutionVisitor.java &
> MaterializedViewSubstitutionVisitor.java, it's quite common to add a
> compensating Project on top of child node of target(MV-rel) during matching.
> But afterwards the next round matching should be able to handle such a
> compensated Project and match upward along the plan tree. Otherwise we fail
> the matching. After all, the goal of matching is to transform the query and
> let a complete 'target' show up in the transformed query plan.
> I found cases where the compensated Project cannot be properly handled.
> {code:java}
> MV:
> select deptno, sum(salary) + 2, sum(commission)
> from emps
> group by deptno
> Query:
> select deptno, sum(salary) + 2
> from emps
> group by deptno
> {code}
> After matching of the Aggregates, a compensating Project is added, but
> afterwards matching fails to handle it.
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