On Wed, Nov 23, 2011 at 11:25 AM, J Ramesh Kumar <rameshj1977@xxxxxxxxx> wrote:
autovacuum_freeze_max_age (integer)
Hi,
My application is performing 1600 inserts per second and 7 updates per second. The updates occurred only in a small table which has only 6 integer columns. The inserts occurred in all other daily tables. My application creates around 75 tables per day. No updates/deletes occurred in those 75 daily tables (only inserts and drop tables if older than 40 days). Since only inserts in the daily tables, I disabled autovacuum in the conf file and I can see it is off stat using show command.
sasdb=# show "autovacuum";
autovacuum
------------
off
(1 row)
But the autovacuum is running frequently and it impact the performance of my system(high CPU). You can see the autovacuum in the pg_stat_activity.
sasdb=# select current_query from pg_stat_activity where current_query like 'autovacuum%';
current_query
---------------------------------------------------------------------------------------
autovacuum: VACUUM public.xxxxx_17_Oct_11 (to prevent wraparound)
autovacuum: VACUUM public.xxxxx_17_Oct_11 (to prevent wraparound)
autovacuum: VACUUM public.xxxxx_17_Oct_11 (to prevent wraparound)
(3 rows)
Its pretty clear, its to prevent tranx wrap-around.
Specifies the maximum age (in transactions) that a table's pg_class.relfrozenxid field can attain before a VACUUM operation is forced to prevent transaction ID wraparound within the table. Note that the system will launch autovacuum processes to prevent wraparound even when autovacuum is otherwise disabled.
http://developer.postgresql.org/pgdocs/postgres/runtime-config-autovacuum.html
Why the autovacuum is running even though, I disabled ? Am I miss anything ?
And also please share your views on my decision about disable autovacuum for my application. I am planning to run vacuum command daily on that small table which has frequent updates.
Thanks,
Ramesh
