On Fri, Jan 11, 2013 at 1:04 PM, Sahagian, David <david.sahagian@xxxxxxx> wrote: > In regards to 9.1.x, I would like to learn some details of the nature of > “checkpointing” > > === Question 1 === > > - page 123 is dirty > > - "checkpointing" starts > > - page 123 gets written to disk, as part of this checkpoint > > - page 123 gets modified again > > ? Does it get written to disk again, as part of this checkpoint? No, the checkpointer doesn't write it again. > > === Question 2 === > > - page 123 is dirty > > - "checkpointing" starts > > - page 123 gets modified again > > - page 123 gets written to disk, as part of this checkpoint > > ? So does the most recent mod get written to disk, even if that mod is not > committed yet ? Yes, it the most recent version that gets written. The notion of "committed' does not really apply to pages. > === Question 3 === > > > > When does the full-page-writing to WAL happen ? > > Is it after the start of the "checkpointing" or after the finish of the > "checkpointing" ? > The start. Cheers, Jeff -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
