Hi Alvaro,
thanks for your answer and sorry for the delay but I was in vacation.
Alvaro Herrera wrote:
Stefano Nichele escribió:
Hi All,
I have a couple of questions about autovacuum/vacuum behavior.
On my production system, I set autovacuum ON since it's pretty hard to
me find a good timeframe for vacuum (the system is pretty busy over the day)
Last week the system was really slow and running vacuum manually the
performance was really improved.
So now I would like to understand why autovacuum did not work as
expected (at least for me). Any ideas ?
Maybe the autovacuum naptime was set too high. Or perhaps the threshold
and scale settings were too high. Maybe the vacuum_cost_delay for
autovacuum was too high.
Currently I'm still run vacuum but as soon as I can, I'll do other tests.
Why autovacuum (that was OFF) started ? For preventing transaction ID
wraparound ? Is it right that in such case all the tables are
(auto)vacuumed ?
Not necessarily all tables; only those that require a vacuum to prevent
xid wraparound. (It was all tables in 8.1, but this changed in 8.2).
Actually I saw that it autovacuumed all tables (except 2 of 100 tables).
And why during vacuum ? (this is not just a coincidence since occurred
more than one time).
It seems autovacuum was triggered by vacuum.
Cheers,
ste
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