2010/11/1 hubert depesz lubaczewski <depesz@xxxxxxxxxx>: > On Mon, Nov 01, 2010 at 08:13:49PM +0100, Cédric Villemain wrote: >> 2010/11/1 hubert depesz lubaczewski <depesz@xxxxxxxxxx>: >> > On Mon, Nov 01, 2010 at 07:22:50PM +0100, Cédric Villemain wrote: >> >> > as I understand, max number of xlog files in pg_xlog should be ( 1 + 2 * >> >> > checkpoint_segments ). >> >> (2 + checkpoint_completion_target) * checkpoint_segments + 1 >> >> => 291 >> > >> > this is formula gave to me by rhodiumtoad on irc, but we tested with lower >> > checkpoint_completion_target and it didn't change *anything*. >> >> You'll have between 211 and 291 files for 0.1 to 0.9 >> checkpoint_completion_target. >> You'd have more than the number of files given by formula used during >> your tests ? > > yes. we decreased checkpoint_completion_target to 0.5, and the numbers > of xlog segments *did not change*. It should stick at a maximum of 3 * checkpoint_segments + 1, if it exceed it will remove the extra files after. > 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. > > Best regards, > > depesz > > -- > Linkedin: http://www.linkedin.com/in/depesz / blog: http://www.depesz.com/ > jid/gtalk: depesz@xxxxxxxxxx / aim:depeszhdl / skype:depesz_hdl / gg:6749007 > -- Cédric Villemain 2ndQuadrant http://2ndQuadrant.fr/ ; PostgreSQL : Expertise, Formation et Support -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
