On 26 May 2012 01:36, Jeff Janes <jeff.janes@xxxxxxxxx> wrote: > On Fri, May 25, 2012 at 3:04 PM, Ivan Voras <ivoras@xxxxxxxxxxx> wrote: >> Hello, >> >> I'm wondering if there is ia document describing which guarantees (if >> any) PostgreSQL makes about concurrency for various operations? Speaking >> in general (i.e. IO can handle it, number of CPU cores and client >> threads is optimal), are fully concurrent operations (independant and >> non-blocking) possible for: > > By "fully concurrent" do you mean that there is no detectable > sub-linear scaling at all? I'm pretty sure that no such guarantees > can be made. > For concurrent bulk loads, there was severe contention on generating > WAL between concurrent bulk loaders. That is greatly improved in the > upcoming 9.2 release. I was thinking about major exclusive locks in the code paths which would block multiple clients operating on unrelated data (the same questions go for update operations). For example: if the free space map or whole index trees are exclusively locked, things like that. The WAL issue you mention seems exactly like what I was asking about, but are there any others? -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
