jin xing created CALCITE-3256:
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Summary: 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
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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