>Right now, UNION DISTINCT, along with INTERSECT and EXCEPT, have basically no >optimization support whatsoever... > Sorry to be the bearer of bad news, but this isn't going to change just > because you try to label it a bug.
Given the medium, I'll try not to read that in a snarky tone, after all, surely it's not unreasonable to label it a defect for a system not to optimize one of the basic relational primitives. That said, I know well the annoyance when a user cries bug when the system is working as-designed. In any case, I'm at least glad to have resolution; I know that there is no choice but to work around it. For a maximally general work-around given that the union is the essence of a reused view, perhaps a reasonable approach is to switch to Union All and nest it within a Distinct outer query. That seems to produce workable plans in my tests so far. Maybe that could even form the basis of a planner enhancement that wouldn't require a complete refactor. Thanks again, -Nate -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
