On Sun, Aug 23, 2009 at 5:26 PM, Jeff Janes<jeff.janes@xxxxxxxxx> wrote: >>> >>> One problem is as you note. How is the average user supposed to know >>> what is the size of the redo that is generated by a typical >>> transaction? >>> >> >> one way is if there is a way to know how many blocks have been written >> by postgres (even a total is usefull because we can divide that per >> pg_stat_database.xact_commits), maybe >> pg_stat_bgwriter.buffers_checkpoint can give us an idea of that? > > No, you want the amount of WAL data written, not the tablespace data written, > which is what pg_stat_bgwriter gives you. Just look at how fast your pg_xlogs > are being archived and turned over to determine that WAL volume (unless you > have archive_timeout set). mmm... what about turning log_checkpoint on and look at the recycled segments number... (recycled_segments * wal_segment_size) / number of xact commited in that period do that for some days at the same (hopefully peak) hours... > > maybe the code bracketed by the probes > TRACE_POSTGRESQL_WAL_BUFFER_WRITE_DIRTY* should be counted > and reported under one of the stat tables. > +1, at least could be useful for some of us that do not have dtrace -- Atentamente, Jaime Casanova Soporte y capacitación de PostgreSQL Asesoría y desarrollo de sistemas Guayaquil - Ecuador Cel. +59387171157 -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
