On Thu, 2023-11-16 at 22:38 -0500, Tom Lane wrote: > That line of argument also leads to the conclusion that it'd be > okay to expose info about the ordering of the CTE result to the > upper planner. [...] The fence is sort of one-way > in this line of thinking: information can propagate up to the outer > planner level, but not down into the CTE plan. > > Thoughts?
That agrees with my intuition about MATERIALIZED CTEs. I think of them as "first calculate the CTE, then calculate the rest of the query" or an ad-hoc temporary table for the duration of a query. I would expect the upper planner to know estimates and other data about the result of the CTE. Yours, Laurenz Albe
