Re: Strange performance degradation

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A. Kretschmer wrote:
In response to Lorenzo Allegrucci :
Hi all,

I'm experiencing a strange behavior with my postgresql 8.3:
performance is degrading after 3/4 days of running time but if I
just restart it performance returns back to it's normal value..
In normal conditions the postgres process uses about 3% of cpu time
but when is in "degraded" conditions it can use up to 25% of cpu time.
The load of my server is composed of many INSERTs on a table, and
many UPDATEs and SELECT on another table, no DELETEs.
I tried to run vacuum by the pg_maintenance script (Debian Lenny)
but it doesn't help. (I have autovacuum off).

Bad idea. Really.

Why running vacuum by hand is a bad idea?
vacuum doesn't solve anyway, it seems only a plain restart stops the
performance degradation.

So, my main question is.. how can just a plain simple restart of postgres
restore the original performance (3% cpu time)?

You should enable autovacuum.

And you should run vacuum verbose manually and see the output.

below is the output of vacuum analyze verbose
(NOTE: I've already run vacuum this morning, this is a second run)

DETAIL:  A total of 58224 page slots are in use (including overhead).
58224 page slots are required to track all free space.
Current limits are:  2000000 page slots, 1000 relations, using 11784 kB.

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