On Wednesday 17 November 2010 02:04:28 Tom Lane wrote: > Andres Freund <andres@xxxxxxxxxxx> writes: > > On Wednesday 17 November 2010 01:51:28 Tom Lane wrote: > >> Well, there's a forced fsync after writing the last page of an xlog > >> file, but I don't believe that proves that more than 16MB of xlog > >> buffers is useless. Other processes could still be busy filling the > >> buffers. > > > > Maybe I am missing something, but I think the relevant > > AdvanceXLInsertBuffer() is currently called with WALInsertLock held? > > The fsync is associated with the write, which is not done with insert > lock held. We're not quite that dumb. Ah, I see. The XLogWrite in AdvanceXLInsertBuffer is only happening if the head of the buffer gets to the tail - which is more likely if the wal buffers are small... Andres -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
