kumarUjjawal opened a new pull request, #22736:
URL: https://github.com/apache/datafusion/pull/22736
## Which issue does this PR close?
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- Closes #21619
## Rationale for this change
Identical uncorrelated scalar subqueries are deduplicated, but this is not
correct when the subquery contains volatile expressions such as `random()`.
For example, `(SELECT random()) - (SELECT random())` must evaluate both
scalar subquery occurrences independently.
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Why are you proposing this change? If this is already explained clearly in
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## What changes are included in this PR?
- Detect volatility inside subquery plans.
- Avoid CSE deduplication for volatile scalar subqueries.
- Keep volatile scalar subquery occurrences distinct in physical planning.
- Preserve deduplication for non-volatile scalar subqueries.
- Add regression coverage for same-node, cross-node, nested, and
shared-expression cases.
- Update upgrade notes for the public `ExecutionProps` field type.
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## Are these changes tested?
Yes
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## Are there any user-facing changes?
Yes. Queries with repeated volatile scalar subqueries now evaluate each
occurrence independently instead of incorrectly reusing one result.
There is also a public API type change for
`ExecutionProps::subquery_indexes`, documented in the upgrade notes.
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