Re: pg_autovacuum w/ dbt2

Mark Wong wrote:

>After all this time I finally got around to vacuuming the database
>with dbt2 with pg_autovacuum. :)
> http://www.osdl.org/projects/dbt2dev/results/dev4-010/215/
>
>
Thanks!

>Doesn't look so good though, probably because I'm not using optimal
>settings with pg_autovacuum. So far I have only tried the default
>settings (running without any arguments, except -D).
>
>
I don't know what you mean by "Not Good" since I don't have graphs from
a similar test without pg_autovacuum handy. Do you have a link to such
a test?

As for better pg_autovacuum settings, It appears that the little
performance dips are happening about once every 5 minutes, which if I
remember correctly is the default sleep time. You might try playing
with the lazy vacuum settings to see if that smooths out the curve.
Beyond that all you can do is play with the thresholds to see if there
is a better sweet spot than the defaults (which by the way I have no
confidence in, they were just conservative guesses)

>The only thing that's peculiar is a number of unexpected rollbacks
>across all of the transactions. I suspect it was something to do with
>these messages coming from pg_autovacuum:
>
>[2004-12-20 15:48:18 PST] ERROR: Can not refresh statistics information from the database dbt2.
>[2004-12-20 15:48:18 PST] The error is [ERROR: failed to re-find parent key in "pk_district"
>]
>
>
Not sure what this is all about, but if you turn up the debug level to 4
or greater (pg_autovacuum -d4), pg_autovacuum will log the query that is
causing the problems, that would be helpful output to have.

>This is with 8.0rc1. I can get rc2 installed since it just came out.
>So let me know what I can try and what not.
>
>
I don't think anything has changed for pg_autovacuum between rc1 and rc2.

thanks again for the good work!!!