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https://issues.apache.org/jira/browse/IGNITE-29053?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18116335#comment-18116335
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Vladislav Pyatkov commented on IGNITE-29053:
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Merged e20453758e4dcde264fb73a0d53c1a927647726f
> SQL Calcite: Handle ORDER BY in recursive CTE
> ---------------------------------------------
>
> Key: IGNITE-29053
> URL: https://issues.apache.org/jira/browse/IGNITE-29053
> Project: Ignite
> Issue Type: Improvement
> Reporter: Vladislav Pyatkov
> Assignee: Vladislav Pyatkov
> Priority: Major
> Labels: calcite, ignite-2, sql
> Time Spent: 20m
> Remaining Estimate: 0h
>
> h3. Motivation
> A recursive CTE with an _ORDER BY_ clause applied to its _UNION_ fails
> validation in the Calcite SQL engine:
> {code}
> WITH RECURSIVE numbers(n) AS (
> SELECT 1
> UNION ALL
> SELECT n + 1
> FROM numbers
> WHERE n < 3
> ORDER BY n
> )
> SELECT n
> FROM numbers
> ORDER BY n;
> {code}
> The same issue occurs when the RECURSIVE keyword is omitted.
> The query fails with:
> {noformat}
> Object 'NUMBERS' not found
> {noformat}
> Calcite rewrites the internal ORDER BY into a wrapping SELECT, preventing
> correct recursive CTE recognition and scope resolution.
> h3. Definition of done
> * Accept and ignore ORDER BY applied to the recursive UNION when no
> row-limiting clause is present. The example should return 1, 2, 3.
> * Reject an internal ORDER BY combined with FETCH, LIMIT, or OFFSET with
> UNSUPPORTED_OPERATION and a clear error message.
> * Apply the same behavior with and without the RECURSIVE keyword.
> * Preserve ordering and row limiting in non-recursive CTEs and in queries
> consuming the recursive CTE.
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