On 8 June 2012 09:14, Kyotaro HORIGUCHI <horiguchi.kyot...@lab.ntt.co.jp> wrote:
> The requirement for this patch is as follows. > > - What I want to get is similarity of the behaviors between > master and (hot-)standby concerning checkpoint > progression. Specifically, checkpoints for streaming > replication running at the speed governed with > checkpoint_segments. The work of this patch is avoiding to get > unexpectedly large number of WAL segments stay on standby > side. (Plus, increasing the chance to skip recovery-end > checkpoint by my another patch.) Since we want wal_keep_segments number of WAL files on master (and because of cascading, on standby also), I don't see any purpose to triggering more frequent checkpoints just so we can hit a magic number that is most often set wrong. ISTM that we should avoid triggering a checkpoint on the master if checkpoint_segments is less than wal_keep_segments. Such checkpoints serve no purpose because we don't actually limit and recycle the WAL files and all it does is slow people down. Also, I don't believe that throwing more checkpoints makes it more likely we can skip shutdown checkpoints at failover. -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
