Scott Marlowe <scott.marlowe@xxxxxxxxx> wrote: > On Wed, Dec 21, 2011 at 10:50 AM, Rafael Martinez > <r.m.guerrero@xxxxxxxxxxx> wrote: >> As long as I know, all the databases are using the default, "read >> committed". > > Note that backups run in serializable mode. In 9.1 they default to running in "repeatable read". You can choose the --serializable-deferrable option, which runs at the serializable transaction isolation level, sort of. It does that by waiting for a "safe" snapshot and then running the same as a repeatable read transaction -- so either way you have none of the overhead of the new serializable transactions. Besides that, almost all of the additional RAM usage for the new serializable implementation is in shared memory. As you can see in the graphs from Rafael, the difference isn't very dramatic as a percentage of a typical production configuration. -Kevin -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
