mihailotim-db opened a new pull request, #55606:
URL: https://github.com/apache/spark/pull/55606
## What changes were proposed in this pull request?
Wrap outer star expansion results in Alias in
ResolveReferences.expandStarExpressionInValidOperators. When a targeted star
(e.g. t1.*)
inside a scalar subquery resolves from the outer scope, each expanded
attribute is now wrapped in Alias(OuterReference(attr), name)
instead of bare OuterReference(attr).
For struct star expansion (e.g. t1.s.*), the expansion already produces
Alias(GetStructField(...), fieldName). In that case we wrap
only the inner child with OuterReference, preserving the existing Alias to
avoid double aliasing.
## Why are the changes needed?
Without the Alias, the OuterReference attribute's ExprId leaks into the
subquery scope via Project.output (since
OuterReference.toAttribute strips the wrapper). When a derived table wraps
the outer star expansion, downstream operators (e.g. SELECT
*) reference this leaked ExprId directly, which can cause issues with
expression ID tracking. Wrapping in Alias gives each outer
reference a fresh ExprId in the subquery's scope.
Example:
SELECT (SELECT * FROM (SELECT t1.* FROM VALUES(2) AS t2(col1) LIMIT 1))
FROM VALUES(1) AS t1(col1)
## Does this PR introduce any user-facing change?
No.
## How was this patch tested?
Added SQL golden file tests in scalar-subquery-select.sql:
- Outer star expansion (t1.* from outer scope)
- Outer struct star expansion (t1.s.*)
- Untargeted star does NOT expand from outer scope
- Inner scope wins when both match
- Outer star through derived table wrapper
Also fixed a pre-existing missing semicolon in the test file.
## Was this patch authored or co-authored using generative AI tooling?
Generated-by: Claude Code (claude-opus-4-6)
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