mohammadnaqvi04 opened a new pull request, #25008:
URL: https://github.com/apache/datafusion/pull/25008
## Which issue does this PR close?
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- Closes #24960.
## Rationale for this change
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See #24960.
## What changes are included in this PR?
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Correlated `EXISTS`/`IN` subqueries had count-bug compensation available but
never turned it on.
* Turn on count-bug compensation for correlated `EXISTS`/`IN` subqueries.
* When compensation is needed, decorrelate into a `LEFT JOIN` and substitute
the correct value instead of dropping the row.
* Fix a related bug in the `IN` case, where the comparison value could
wrongly affect which rows the join matched, corrupting results for rows with a
real correlated match.
* Make unsupported join shapes fail loudly instead of silently falling back
to incorrect behavior.
## What is the testing strategy for this PR?
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Added thirteen sqllogictest cases in `subquery.slt` and one unit test.
They cover `EXISTS`, `NOT EXISTS`, and `IN`. Each is tested standalone and
embedded in an `OR`. Each is also tested against an aggregate with a zero
default and one with a `NULL` default.
Ran the full `datafusion`, `datafusion-cli`, and `datafusion-sqllogictest`
suites, and `./dev/rust_lint.sh`.
## Are there any user-facing changes?
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None, except in the sense that this fixes a user-visible bug.
## AI Usage
_AI was used during development of this PR, primarily to help review the
test suite and verify test cases against the implemented fix._
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