tomsanbear opened a new pull request, #23098: URL: https://github.com/apache/datafusion/pull/23098
## Which issue does this PR close? - Closes #23097. ## Rationale for this change `WITH RECURSIVE t(n) AS (...)` failed to plan because the CTE's declared column-list names (the `t(n)` part) were never applied to the recursive working relation. They were applied (via `apply_table_alias`) only after the whole CTE plan was built, but the working table is derived from the static term's schema *before* that — so the self-reference couldn't resolve the declared names and planning failed with `Schema error: No field named n. Valid fields are t."Int64(1)".`. PostgreSQL and DuckDB accept the query; aliasing inside the static `SELECT` (`SELECT 1 AS n`) was the only workaround. ## What changes are included in this PR? Apply the column-list aliases to the static term inside `recursive_cte()`, before the work table is created, so the working relation and the self-reference carry the declared names. The caller now applies only the relation-name alias on the recursive path (the columns are already applied), avoiding a redundant projection on top of the `RecursiveQuery` node. The non-UNION fallback applies the aliases directly; non-recursive CTEs are unchanged. A column/alias-count mismatch is now reported at the static term — a clearer error than the previous "No field named …". ## Are these changes tested? Yes, added `cte.slt` cases for single- and multi-column column-list recursive CTEs (asserting the recursion produces the expected rows), `UNION (DISTINCT)`, the arity-mismatch error, and an `EXPLAIN` locking the plan shape (no extra projection over `RecursiveQuery`). ## Are there any user-facing changes? `WITH RECURSIVE t(n) AS (...)` and multi-column column lists now plan and execute correctly, matching PostgreSQL/DuckDB. No API changes. *Note: this pull request was created together with AI tools (claude code), the full diff was reviewed by myself in full prior to submission* -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
