On 2021-Mar-23, Robert Haas wrote: > Likewise, the XXX comment you added to max_parallel_hazard_walker > claims that some of the code introduced there is to compensate for an > unspecified bug in the rewriter. I'm a bit skeptical that the comment > is correct, and there's no way to find out because the comment doesn't > say what the bug supposedly is, but let's just say for the sake of > argument that it's true. Well, you *could* have fixed the bug, but > instead you hacked around it, and in a relatively expensive way that > affects every query with a CTE in it whether it can benefit from this > patch or not. That's not a responsible way of maintaining the core > PostgreSQL code.
I think the CTE bug is this one: https://www.postgresql.org/message-id/flat/CAJcOf-fAdj=ndkmsrhqzndm-o13ny4dl6xgcevdx5xvbbi0...@mail.gmail.com while I can't disagree with the overall conclusion that it seems safer to revert parallel INSERT/SELECT given the number of alleged problems, it is true that this bug exists, and has gone unfixed. -- Álvaro Herrera Valdivia, Chile
