Julien Rouhaud <julien.rouh...@dalibo.com> writes: > Shouldn't we also check "parallel_degree < max_worker_process" ?
> There's no need to compute any further than that. I think the best fix > would be to add a CheckHook or AssignHook on max_parallel_degree GUC to > make sure it's not more than max_worker_process. Please, let's not go there. Interdependent checks on GUC values are far harder to get right than you think. It's far better to design the GUC specifications so that it doesn't matter. For an example whereof I speak, check the sordid history of commit ee1e5662d8d83307 ("Auto-tune effective_cache size to be 4x shared buffers"), which eventually got reverted after a huge amount of thrashing trying to make it work consistently. Admittedly, that was trying to make the default value of GUC X depend on GUC Y, but I think checking whether X <= Y would have many of the same problems. The core issue is you don't know which one's going to get set first. In this particular case I think it'd be fine to document that the effective amount of parallelism is Min(parallel_degree,max_worker_process). regards, tom lane -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers