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…ueries When a correlated subquery refers to the outer query from two of its relations through columns with the same name, `SubqueryAlias` gives those columns unique aliases (`k`, `k:1`), but `replace_qualified_name` rewrote the pulled-up join filter by column name only, so both columns referred to the first one and the query returned wrong results. This affected EXISTS, NOT EXISTS, IN and scalar subqueries. Map each correlated column to the name it has in the alias's schema, found by its position in the decorrelated subquery's schema. Columns the schema only has under a derived table's alias keep the name-based mapping.
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alamb
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Oct 28, 2026
alamb
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Thank you for your contribution; Sorry I don't think this is the right approach
As I mentioned elsewhere (sorry for the repeated content) I don't think we should be trying to patch these subquery cases to make them work; Instead I think we should make the query error otherwise i worry we just open ourselves up to more wrong results bugs. To make it work and have confidence it will be correct, I think we need a more general approach than patches. See here for details
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Which issue does this PR close?
Rationale for this change
See issue #26234.
What changes are included in this PR?
When a correlated subquery refers to the outer query from two of its relations through columns with the same name,
SubqueryAliasgives those columns unique aliases (k,k:1), butreplace_qualified_namerewrote the pulled-up join filter by column name only, so both columns referred to the first one and the query returned wrong results. This affected EXISTS, NOT EXISTS, IN and scalar subqueries.Map each correlated column to the name it has in the alias's schema, found by its position in the decorrelated subquery's schema. Columns the schema only has under a derived table's alias keep the name-based mapping.
What is the testing strategy for this PR?
Introducing new tests for the affected subqueries.
Are there any user-facing changes?
Correcting the behaviour of queries that previously produced the wrong results.