morrySnow opened a new pull request, #67541:
URL: https://github.com/apache/doris/pull/67541
### What problem does this PR solve?
Issue Number: None
Related PR: None
Problem Summary:
`AddProjectForJoin` inserts a `LogicalProject` above every Join before
classic Cascades exploration. Most of these Projects contain only Slots, but
the standalone `PushDownProjectThroughSemiJoin` and
`PushDownProjectThroughInnerOuterJoin` exploration rules still expand child
groups and assemble temporary Plans before their predicates reject the match.
This creates substantial CPU and allocation overhead as the Memo grows.
This change:
- extracts the existing Project normalization logic into a shared helper;
- invokes that helper only when a Project-aware Join reorder rule is ready
to produce an alternative;
- covers inner associate/asscom/exchange, outer associate/asscom, and
semi-join transpose paths;
- removes the two standalone PushDown rule factories from classic
`OTHER_REORDER_RULES`;
- keeps the standalone rules and their `AFTER_DPHYP_REORDER_RULES`
registration unchanged for DPHyp.
Local FE-only validation:
- 24 targeted FE unit tests passed, including helper edge cases, all
Project-aware reorder families, the existing standalone rule tests, and a
complete `AddProjectForJoin -> classic optimizer` path.
- TPC-H 22, TPC-DS 99, and one DPHyp smoke query produced identical
optimizer mode, physical Plan fingerprint, root cost, and limit state between
the registered baseline and candidate.
- The candidate removed 162 redundant Memo expressions across six workload
queries without changing the selected Plan.
- Across 12 STAR/DENSE × SLOT/COMPLEX × 3/8/16-table JMH pairs, candidate
mean planning time and allocation/op were lower in every configuration. The
geometric baseline/candidate ratios were 1.066x/1.114x for Slot Projects and
1.698x/1.617x for Complex Projects.
- In a 9-table JFR workload, candidate main-thread allocation fell 16.2%,
matcher allocation 34.4%, Plan-assembly allocation 39.4%, and
`withGroupExprLogicalPropChildren` allocation 40.7%.
All temporary instrumentation, JMH/JFR harnesses, and local analysis
documents were removed from this commit.
### Release note
Reduce Nereids classic Cascades planning overhead for queries with multiple
joins.
### Check List (For Author)
- Test
- [ ] Regression test
- [x] Unit Test
- [ ] Manual test (add detailed scripts or steps below)
- [ ] No need to test or manual test. Explain why:
- [ ] This is a refactor/code format and no logic has been changed.
- [ ] Previous test can cover this change.
- [ ] No code files have been changed.
- [ ] Other reason
- Behavior changed:
- [ ] No.
- [x] Yes. Classic Cascades now normalizes Complex Projects while
producing Join reorder alternatives instead of through standalone exploration
rules. DPHyp behavior is unchanged.
- Does this need documentation?
- [x] No.
- [ ] Yes.
### Check List (For Reviewer who merge this PR)
- [ ] Confirm the release note
- [ ] Confirm test cases
- [ ] Confirm document
- [ ] Add branch pick label
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