On Thu, Mar 27, 2025 at 5:38 PM Robert Haas <robertmh...@gmail.com> wrote: > It's not a problem if UNION ALL is used within the initial_query and > it's not a problem if UNION ALL is used within the iterated_query. But > you can't apply ORDER BY to the result of the UNION, because the UNION > is kind of fake -- we're not running the UNION as a single query, > we're running the two halves separately, the first once and the second > as many times as needed.
I understand that we can only apply ORDER BY separately in the initial/iterated query. What disturbs me here is that the UNION operator has associativity precedence over the ORDER BY only when inside a recursive CTE. Consider the following query: SELECT 1 UNION SELECT 1 GROUP BY 1; It returns 2 rows. The GROUP BY clause attaches to the second selectStmt without the need to add parenthesis. I would expect the same syntax inside a recursive CTE.
