LLLLLL302311 opened a new pull request, #66781:
URL: https://github.com/apache/doris/pull/66781
### What problem does this PR solve?
Problem Summary:
When a query contains many structurally-identical uncorrelated scalar
subqueries
that reference the same CTE (e.g. `(SELECT dt FROM deal_dt)` repeated
hundreds of
times), `SubqueryToApply` generated one `LogicalApply` per occurrence.
This blew up
the Nereids optimization search space and caused the planner to time out
(`Nereids cost too much time`), while these queries planned fine on the
legacy optimizer.
This PR groups reusable scalar subqueries within the same
`LogicalFilter`/`LogicalProject`
by `(cteId, cte name, projection, data type, nullable)` and builds a
single `Apply` for a
representative, letting the other occurrences reuse its output. Correlated
subqueries,
subqueries needing type coercion, `DISTINCT`/multi-column projections and
non-CTE
subqueries are excluded to preserve semantics.
### Release note
None
### Check List (For Author)
- Test
- [x] Unit Test
- [ ] Regression test
- [ ] Manual test
- [ ] No need to test or manual test.
- Behavior changed:
- [x] No.
- Does this need documentation?
- [x] No.
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