On Thu, May 24, 2012 at 12:06 AM, Hugo <Nabble> <hugo.t...@gmail.com> wrote:
> Hi everyone, > > We have a production database (postgresql 9.0) with more than 20,000 > schemas > and 40Gb size. In the past we had all that information in just one schema > and pg_dump used to work just fine (2-3 hours to dump everything). Then we > decided to split the database into schemas, which makes a lot of sense for > the kind of information we store and the plans we have for the future. The > problem now is that pg_dump takes forever to finish (more than 24 hours) > and > we just can't have consistent daily backups like we had in the past. When I > try to dump just one schema with almost nothing in it, it takes 12 minutes. > When I try to dump a big schema with lots of information, it takes 14 > minutes. So pg_dump is clearly lost in the middle of so many schemas. The > load on the machine is low (it is a hot standby replica db) and we have > good > configurations for memory, cache, shared_buffers and everything else. The > performance of the database itself is good, it is only pg_dump that is > inefficient for the task. I have found an old discussion back in 2007 that > seems to be quite related to this problem: > > > http://postgresql.1045698.n5.nabble.com/5-minutes-to-pg-dump-nothing-tp1888814.html > > It seems that pg_dump hasn't been tested with a huge number of schemas like > that. Does anyone have a solution or suggestions? Do you know if there are > patches specific for this case? > How many total relations do you have? I don't know if there is a limit to the number of schemas, but I suspect when you went from one schema to 20,000 schemas, you also went from N relations to 20000*N relations. Somewhere between 100,000 and 1 million total relations, Postgres starts to have trouble. See this thread: http://permalink.gmane.org/gmane.comp.db.postgresql.performance/33254 (Why is it that Google can't find these archives on postgresql.org?) Craig > Thanks in advance, > Hugo > > ----- > Official Nabble Administrator - we never ask for passwords. > -- > View this message in context: > http://postgresql.1045698.n5.nabble.com/pg-dump-and-thousands-of-schemas-tp5709766.html > Sent from the PostgreSQL - performance mailing list archive at Nabble.com. > > -- > Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-performance >
