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. > > 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. 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 -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
