Hello Guillaume! Sat, 09 Jul 2011 10:33:03 +0200, you wrote: > Hi, > On Sat, 2011-07-09 at 09:25 +0200, Gael Le Mignot wrote: >> [...] >> We are running a PostgreSQL 8.4 database, with two tables containing a >> lot (> 1 million) moderatly small rows. It contains some btree indexes, >> and one of the two tables contains a gin full-text index. >> >> We noticed that the autovacuum process tend to use a lot of memory, >> bumping the postgres process near 1Gb while it's running. >> > Well, it could be its own memory (see maintenance_work_mem), or shared > memory. So, it's hard to say if it's really an issue or not. > BTW, how much memory do you have on this server? what values are used > for shared_buffers and maintenance_work_mem? maintenance_work_mem is at 16Mb, shared_buffers at 24Mb. The server currently has 2Gb, we'll add more to it (it's a VM), but we would like to be able to make an estimate on how much memory it'll need for a given rate of INSERT into the table, so we can estimate future costs. >> I looked in the documentations, but I didn't find the information : do >> you know how to estimate the memory required for the autovacuum if we >> increase the number of rows ? Is it linear ? Logarithmic ? >> > It should use up to maintenance_work_mem. Depends on how much memory you > set on this parameter. So, it shouldn't depend on data size ? Is there a fixed multiplicative factor between maintenance_work_mem and the memory actually used ? >> Also, is there a way to reduce that memory usage ? > Reduce maintenance_work_mem. Of course, if you do that, VACUUM could > take a lot longer to execute. >> Would running the autovacuum more frequently lower its memory usage ? >> > Yes. Thanks, we'll try that. Regards, -- Gaël Le Mignot - gael@xxxxxxxxxxxxxxxx Pilot Systems - 9, rue Desargues - 75011 Paris Tel : +33 1 44 53 05 55 - www.pilotsystems.net Gérez vos contacts et vos newsletters : www.cockpit-mailing.com -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
