Hi: On Fri, Jul 29, 2016 at 10:35 AM, Moreno Andreo <moreno.and...@evolu-s.it> wrote: > After Andreas post and thinking about it a while, I went to the decision > that it's better not to use RAM but another persistent disk, because there > can be an instant between when a WAL is written and it's fsync'ed, and if a > failure happens in this instant the amount of data not fsync'ed is lost. Am > I right?
With the usual configuration, fsync on, etc.. what postgres does is to write and sync THE WAL before commit, but it does not sync the table pages. Should anything bad (tm) happen it can replay the synced wal to recover. If you use a ram disk for WAL and have a large enough ram cache you can lose a lot of data, not just from the last sync. At the worst point you could start a transaction, create a database, fill it and commit and have everything in the ram-wal and the hd cache, then crash and have nothing on reboot. Francisco Olarte. -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
