Tomas Vondra <tv@xxxxxxxx> writes: > Dne 3.4.2011 02:45, Tom Lane napsal(a): >> I wonder whether the discrepancy relates to having to produce >> full-page-image WAL entries during the first touch of a page during the >> pgbench run, versus having already done so in initialization. If you >> force a checkpoint after the init step, do the results change? > Yes, a forced CHECKPOINT results in a much more xlog data in case of the > archive level. Without the checkpoint there was about 5MB, now there is > about about 90MB (a fet kB more than with the minimal wal level). > Hmmm, I'm wondering which of these two cases is more apropriate when > comparing wal levels - with the checkpoint or without it? I believe the > one with checkpoint, as checkpoints happen all the time anyway. Well, both of them are boundary cases --- in a realistic situation you'd have some but not all pages already dirty since the last checkpoint. The important point here is that you had non-comparable starting conditions. regards, tom lane -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
