On 8/21/23 00:15, Adrian Klaver wrote:
On 8/20/23 12:10, Rihad wrote:
On 8/20/23 20:22, Adrian Klaver wrote:
On 8/18/23 22:35, Rihad wrote:
On 8/17/23 13:01, rihad wrote:
Hi, all. After calling pg_stat_reset all statistics used by autovacuum got zeroed, and started accumulating from scratch. Some tables get acted upon properly, some don't.
Self-replying: yup, it seems there's an arbitrary limit of 100K of n_live_tup after which autovac/analyze kicks in, or it seems so.
To know rather then guess read:
https://www.postgresql.org/docs/current/routine-vacuuming.html#AUTOVACUUM
Sure, I read it before asking.
Taking the first table in the list as an example:
relname | n_live_tup | n_dead_tup | left | n_mod_since_analyze | left
--------------------------+------------+------------+----------+---------------------+--------
fooooooooooo | 32781 | 240663 | -234057 | 513265 | -509937
n_dead_tup (not the actual value, but some time after calling pg_stat_reset) is much larger than 20% of n_live_tup 32781, and n_mod_since_analyze is much larger than 10% of it.
Yet it is kept unvacuumed and unanalyzed for a long time.
autovacuum_(vacuum|analyze)_threshold is 50.
What am I missing?
Hard to say without seeing the actual settings in postgresql.conf that match:
https://www.postgresql.org/docs/current/runtime-config-autovacuum.html#GUC-AUTOVACUUM-VACUUM-SCALE-FACTOR
Most importantly:
autovacuum
and
track_counts
https://www.postgresql.org/docs/current/runtime-config-statistics.html#GUC-TRACK-COUNTS
They are both on and set as per default. Autovac/analyze continue running on some tables after pg_stat_reset. Just not on all of them, even thought they should judging by live/dead tuples calculation.
foo=> show track_counts;
track_counts
--------------
on
(1 row)
foo=> show autovacuum;
autovacuum
------------
on
(1 row)
There are still many tables waiting for their turn, which is long due.
Although there are some tables having only 60-70 (not 60-70K) n_live_tup that have had autovacuum run on them. Weird.
