pratham76 opened a new pull request, #58656:
URL: https://github.com/apache/spark/pull/58656
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### What changes were proposed in this pull request?
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`RewritePredicateSubquery` turns a predicate subquery in a `Filter` into a
semi/anti join, using
the correlated predicates that `PullupCorrelatedPredicates` hoisted out of
the subquery as the
join condition. Nested existential subqueries in that condition were all
rewritten into existence
joins on top of the **outer** plan. This PR rewrites each of them against
the plan that actually
produces the attributes it references:
* references the subquery plan and not the outer plan -> the existence join
is built on top of the
subquery plan;
* otherwise -> on top of the outer plan, as before;
* references both plans -> left in the join condition, where both plans are
in scope (it cannot be
rewritten on either side).
Concretely, `rewriteExistentialExprWithAttrs` gains a `canRewrite` predicate
so a caller can
rewrite a subset of the nested subqueries, and two helpers
(`rewriteExistentialExprInJoinCondition` /
`rewriteExistentialExprInSubqueryPlan`) route each
nested subquery to the correct side. All four semi/anti join rewrites
(`EXISTS`, `NOT EXISTS`,
`IN`, `NOT IN`) use them.
### Why are the changes needed?
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A correlated predicate that is a disjunction is hoisted out of the subquery
as a whole, so it can
carry a nested existential subquery with it. That nested subquery may
reference the subquery plan,
in which case building its existence join on top of the outer plan produces
a join whose condition
references an attribute that neither of its children can produce, i.e. a
plan node that references
non-reachable attributes:
```sql
select *
from (values (1), (2), (3)) as t1(a)
where exists (
select c1
from (values (1), (8), (9)) as t2(c1)
where a = c1
or c1 in (select col1 from (values (3), (9)) as t3(col1))
);
```
```
[INTERNAL_ERROR] Couldn't find c1#25 in [a#24,col1#26] SQLSTATE: XX000
```
The optimized plan shows the invalid node (`!Join`), where the existence
join for
`c1 IN (SELECT col1 FROM t3)` sits on top of the outer plan and its
condition references `c1`,
which is only produced by the subquery plan on the right of the semi join:
```
Project [a#9]
+- Join LeftSemi, ((a#9 = c1#10) OR exists#12)
:- !Join ExistenceJoin(exists#12), (c1#10 = col1#11)
: :- LocalRelation [a#9]
: +- LocalRelation [col1#11]
+- LocalRelation [c1#10]
```
With this PR the existence join is built on top of the subquery plan, which
produces `c1`:
```
Project [a#9]
+- Join LeftSemi, ((a#9 = c1#10) OR exists#12)
:- LocalRelation [a#9]
+- Join ExistenceJoin(exists#12), (c1#10 = col1#11)
:- LocalRelation [c1#10]
+- LocalRelation [col1#11]
```
and the query returns `1, 2, 3`, which is what PostgreSQL and DuckDB return.
The same failure affects `NOT EXISTS`, `IN` and `NOT IN` subqueries, and
nested `IN`, `NOT IN` and
`EXISTS` subqueries; a nested subquery correlated to the subquery it is
nested in produced the
same invalid plan but happened to avoid the error when the nested relation
was empty at runtime,
because the invalid condition was then never bound.
### Does this PR introduce _any_ user-facing change?
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Yes. Queries of the shape above failed with `INTERNAL_ERROR` and now return
the correct result.
### How was this patch tested?
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Existing UTs, additional tests have been added
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Claude Code (Claude Sonnet 4.5)
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