Обсуждение: synchronous_commit and wal_writer_delay
Does a synchronous_commit force WAL to be committed to disk or does it just WAIT for WAL to be committed according to WAL's set frequency to write ?
i.e. if I set wal_writer_delay=200ms and set synchronous_commit=on, will each commit wait for upto 200ms before committing ?
On Tue, Jul 26, 2011 at 1:39 PM, A J <s5aly@yahoo.com> wrote: > Does a synchronous_commit force WAL to be committed to disk or does it just > WAIT for WAL to be committed according to WAL's set frequency to write ? > i.e. if I set wal_writer_delay=200ms and set synchronous_commit=on, will > each commit wait for upto 200ms before committing ? > no, that is synchronous... if you set wal_writer_delay=200ms and set synchronous_commit=off then the commit will not be wal-safe (meaning it won't resist a server crash and you will lose data) for a short period of time (200ms in this example) but you shouldn't be setting synchronous_commit on postgresql.conf normally but from the application -- Jaime Casanova www.2ndQuadrant.com Professional PostgreSQL: Soporte 24x7 y capacitación