On Thu, Mar 2, 2017 at 3:54 PM, Amit Kapila <amit.kapil...@gmail.com> wrote: > On Thu, Mar 2, 2017 at 3:50 PM, Robert Haas <robertmh...@gmail.com> wrote: >> On Tue, Feb 28, 2017 at 5:25 PM, Amit Kapila <amit.kapil...@gmail.com> wrote: >>> When such a function (that contains statements which have parallel >>> plans) is being executed as part of another parallel plan, it can >>> allow spawning workers unboundedly. Assume a query like select * >>> from t1 where c1 < func1(), this can use parallel scan for t1 and >>> then in master backend, during partial scan of t1, it can again spawn >>> new set of workers for queries inside func1(), this can happen >>> multiple times if parallel query inside func1() again calls some other >>> function func2() which has parallel query. Now, this might be okay, >>> but today such a situation doesn't exist that Gather execution can >>> invoke another Gather node, so it is worth to consider if we want to >>> allow it. >> >> If we want to prohibit that, the check in standard_planner can be >> changed from !IsParallelWorker() to !IsInParallelMode(), but I'm not >> 100% sure whether that's an improvement or not. > > I am not sure how you can achieve that by just changing > standard_planner() code, because the plans of statements inside pl can > be cached in which case it will not try to regenerate the plan.
Oh, good point. >> I would be inclined >> to leave it alone unless we get several votes to change it. > > Okay, not a problem. Cool. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
