On 02/23/2012 09:35 AM, Alessandro Gagliardi wrote:
I should have been more clear. I virtually never delete or do updates, but I insert a lot. So the table does change quite a bit, but only in one direction.
I was unable to disable autovacuum universally (due to the cant_change_runtime_param error) but I was able to disable it on individual tables. Still, I know this is heavy handed and sub-optimal. I tried set autovacuum_naptime='6min' but got the same 55P02 error. Should/can I set that per table?
I did look at autovacuum_vacuum_threshold and autovacuum_vacuum_scale_factor but couldn't make sense out of them. (Besides, I'd probably get the same 55P02 error if I tried to change them.)
See:
http://www.postgresql.org/docs/current/static/runtime-config-autovacuum.html The documentation has information like "This parameter can only be set in the
postgresql.conf file or on the server command line." that will tell you in advance which settings will fail when you attempt to set them through SQL statements.
But autovacuum is pretty smart about not vacuuming tables until reasonably necessary. And beware that autovacuum is also controlling when to analyze a table. Mass inserts are probably changing the characteristics of your table such that it needs to be analyzed to allow the planner to properly optimize your queries.
Have you identified that vacuum is actually causing a problem? If not, I'd leave it alone. The system tables have a lot of information on table vacuuming and analyzing:
select
relname,
last_vacuum,
last_autovacuum,
last_analyze,
last_autoanalyze,
vacuum_count,
autovacuum_count,
analyze_count,
autoanalyze_count
from
pg_stat_user_tables;
Cheers,
Steve
