Add Explicit Error Handling for Unsupported SQL FETCH Clause in Planner and CLI
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Add guard in SqlToRel::query_to_plan to reject queries with FETCH clause, raising an explicit planner error. Include a regression test for SELECT 1 FETCH NEXT 1 ROW ONLY to ensure the error surfaces. Extend the CLI integration suite to confirm the error is displayed to users. Update SQL guide to note that FETCH is not supported and users should use LIMIT instead.
Clone ORDER BY and LIMIT clauses only for SELECT set expressions. Reuse originals for other branches to improve efficiency and maintain consistency.
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Which issue does this PR close?
Rationale for this change
The
FETCH NEXTclause was being parsed without triggering an error, resulting in the CLI executing queries containing unsupported SQL syntax. This could mislead users into believing the feature is supported and undermine SQL correctness guarantees. Adding explicit handling ensures unsupported syntax fails fast with a clear and consistent error message.What changes are included in this PR?
FETCHclause inSqlToReland return anot_impl_err!when encountered.FETCHis used.FETCH.FETCHclause.Are these changes tested?
Yes. The PR includes:
fetch_clause_is_not_supported) verifying planner behavior.Are there any user-facing changes?
Yes. Queries using the SQL
FETCHclause will now produce a clear error instead of executing unexpectedly. Documentation has been updated to reflect this behavior.LLM-generated code disclosure
This pull request includes code that was generated with assistance from LLM.
All LLM-generated code in this PR has been manually reviewed and tested.