-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Le 01/11/2010 20:54, hubert depesz lubaczewski a Ãcrit : > On Mon, Nov 01, 2010 at 08:31:10PM +0100, CÃdric Villemain wrote: >> It should stick at a maximum of 3 * checkpoint_segments + 1, if it >> exceed it will remove the extra files after. > > if you'd look at the graph you'd notice that it never goes down to 2n+1. > And really - so far I have not yet heard/seen/read any solid reasoning > for 3n instead of 2n. I understand this 3n this way: n "active" WAL files n "recycled-ready-to-use" WAL files checkpoint_completion_target*n WAL being write on disk > >>> also - can you explain why "fraction of total time" (time!) would >>> directly relate to number of xlog files existing in pg_xlog? I mean - >>> you're not the first person to suggest it, but I don't see any way that >>> these two could be related. >> It's guess that while your checkpoint is longer by this factor(X%), >> the number of wal files needed might be multiplied by the same ratio. >> (1+X%) To handle extra files created while the checklpoint is still >> running. > > I'm not sure I understand. Will need to run some tests. Yet - even > assuming (2 + checkpoint_completion_target ) * n - it doesn't explain > why there was no difference in number of segments after decreasing from > 0.9 to 0.5. Does your cluster have enough write ? I think you might have to wait a bit longer to see remaining files being recycled or deleted... > > Best regards, > > depesz > > -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkzPHZcACgkQxWGfaAgowiKQnQCgg7HIAI35mlfySbYY/VptqyjQ kIwAni9DtLqx4j7MFk//1cTf88Dul/4e =NfHT -----END PGP SIGNATURE----- -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
