I usually monitor blks_read and blks_hit (of block level stats), when
the latter is high
I see shared memory is doing a good job, when the former then it also
shows something
Also, database-wide number of commits and rollbacks (btw, Slony has a habit of
calling ROLLBACK when it done nothing -- I wonder if calling ROLLBACK instead
of COMMIT on a SELECT-only transaction is such a win? It certainly blurrs the
image for me. ;)
And a number of clients waiting on a lock.
By the way, one nice thing to have could be counters which record how much
time did it take to load a page into shared memory (less than 1ms, <2ms, <4ms,
<8ms, <16m and so on. Could help fine-tuning things like vacuum cost/delay
and so on. Seen it somewhere in Oraclish stats tables.
Regards,
Dawid