Hi, On 2017-05-05 14:24:07 -0600, Mathieu Fenniak wrote: > The stalls occur unpredictably on my production system, but generally seem > to be correlated with schema operations. My source database has about > 100,000 tables; it's a one-schema-per-tenant multi-tenant SaaS system. I'm unfortunately not entirely surprised you're seeing some issues in that case. We're invalidating internal caches a bit bit overjudiciously, and that invalidation is triggered by schema changes. > I've performed a CPU sampling with the OSX `sample` tool based upon > reproduction approach #1: > https://gist.github.com/mfenniak/366d7ed19b2d804f41180572dc1600d8 It > appears that most of the time is spent in the > RelfilenodeMapInvalidateCallback and CatalogCacheIdInvalidate cache > invalidation callbacks, both of which appear to be invalidating caches > based upon the cache value. I think optimizing those has some value (and I see Tom is looking at that aspect, but the bigger thing would probably be to do fewer lookups. > Has anyone else run into this kind of performance problem? Any thoughts on > how it might be resolved? I don't mind putting in the work if someone > could describe what is happening here, and have a discussion with me about > what kind of changes might be necessary to improve the performance. If you could provide an easily runnable sql script that reproduces the issue, I'll have a look. I think I have a rough idea what to do. Greetings, Andres Freund -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
