Re: Re: significant performance hit whenever autovacuum runs after upgrading from 9.0 -> 9.1

Lonni J Friedman <netllama@gmail.com> writes:
> No, not lots of subqueries or ORDERing, and most queries only touch a
> single table.  However, I'm honestly not sure that I'm following where
> you're going with this.   The problem isn't triggered by explicit
> queries.  I can disable all external access, and simply wait for
> autovacuum to kick off, and the box starts to die.

Can you correlate the performance hit with any specific part of
autovacuum?  In particular, I'm wondering if it matters whether vacuum
is cleaning tables or indexes --- it alternates between the two, and the
access patterns are a bit different.  You could probably watch what the
autovac process is doing with strace to see what it's accessing.

            regards, tom lane