"Edoardo Ceccarelli" <eddy(at)axa(dot)it> writes:
> Given a query that HAS to be executed with a seqscan I have noticed an
> increase in time comparing before and after the vacuum.
This is really hard to believe --- I cannot think of any mechanism that
would result in that effect. Unless the vacuum were flushing the
kernel's disk cache, but the effects of that would only persist for one
scan. You did say that the increased time is repeatable if you do
multiple seqscans after the vacuum?
regards, tom lane