On Wed, 2002-02-27 at 23:21, Jean-Paul ARGUDO wrote:
> > What was the postgresql.conf set to ?
>
> I put parameters in another mail, please watch for it.
>
> > > The "test" is a big batch that computes stuffs in the database.
> > Could you run this batch in smaller chunks to see if PG is slow from the
> > start or does it slow down as it goes ?
>
> The batch starts really fast and past 2 minuts, begins to slow down dramatically
> and never stops to get slower and slower
>
I did a small test run on my home computer (Celeron 350, IDE disks,
untuned 7.2 on RH 7.2)
I made a small table (int,text) with primary key on int and filled it
with values 1-512 for int.
then I ran a python script that updated 10000 random rows in patches of
10 updates.
the first run took
a) 1.28 - 112 tps
as it used seq scans
then I ran VACUUM ANALYZE and next runs were
1. 24 sec - 416 tps
2. 43 sec - 232 tps
3. 71 sec - 140 tps
then I tied the same query and run vacuum in another window manually
each 5 sec.
the result was similar to 1 - 24.5 sec
running vacuum every 10 sec slowed it to 25.1 sec, running every 3 sec
to 24.3 sec. Running vacuum in a tight loop slowed test down to 30.25
sec.
-------------------------
Hannu
