[CALCITE-3256] Add ProjectOnProjectToProjectUnifyRule for materialization matching.

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Duplicate
• Fix Version/s: 1.22.0
• Component/s: core
• Labels: pull-request-available
• Assignee: Jin Xing
• Reporter: Jin Xing
• Created: 16/Aug/19 10:56
• Updated: 28/May/21 10:09
• Resolved: 01/Nov/19 07:23

Description

In current code, below matching fails:

MV:
select deptno, sum(salary) + 2, sum(commission)
from emps
group by deptno

Query:
select deptno, sum(salary) + 2
from emps
group by deptno

The reason is that – after matching of the Aggregates, a compensating Project is added, but afterwards matching fails to handle it.

This issue proposes to add a rule that match when query and target are both Project and query has a compensating Project as a child. After this issue below case can be handled:

Query:
    Project(projects: [$0, +($1, 2)])
      Project(projects: [$1, $3, $4])
        Rel-A
Target:  
    Project(projects: [$1, +($3, 2)])
      Rel-A

Issue Links

• relates to: CALCITE-3334 Refinement for Substitution-Based MV Matching
• links to: GitHub Pull Request #1384