On Fri, Jan 19, 2018 at 10:59 PM, Amit Kapila <amit.kapil...@gmail.com> wrote: > The patch doesn't apply cleanly on the head, but after rebasing it, I > have reviewed and tested it and it seems to be working fine. Apart > from this specific issue, I think we should consider making > nworkers_launched reliable (at the very least for cases where it > matters). You seem to be of opinion that can be a source of subtle > bugs which I don't deny but now I think we are starting to see some > use cases of such a mechanism as indicated by Peter G. in parallel > create index thread. Even, if we find some way for parallel create > index to not rely on that assumption, I won't be surprised if some > future parallelism work would have such a requirement.
Isn't making nworkers_launched reliable exactly what this patch does? It converts the rare cases in which nworkers_launched would have been unreliable into errors, precisely so that code like parallel CREATE INDEX doesn't need to worry about the case where it's inaccurate. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company