On Sat, Nov 15, 2008 at 2:00 AM, Heikki Linnakangas <[EMAIL PROTECTED]> wrote: > Fujii Masao wrote: >> >> Attached is the latest version of Synch Rep patch. > > Why do we need a separate XLogsndRqst variable in shared memory? Don't we > always want to send the WAL up to the same point as we flush it?
It's because the backends flush and send the WAL concurrently. I mean that the backend might request for the WAL to be sent up to the further point while another backend is writing it. If that variable is not separated, the backend cannot request until the former flushing finishes. Regards, -- Fujii Masao NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
