Re: Preventing query from hogging server

"Matthew Nuzum" <matt.followers@gmail.com> writes:
> Here is the query (BTW, there will be a corresponding "max" version of this
> query as well):
> INSERT INTO usage_sessions_min (accountid,atime,sessionid)
> select accountid, min(atime) as atime, sessionid from usage_access
> group by accountid,sessionid;

How many rows in usage_access?  How many groups do you expect?
(Approximate answers are fine.)  What PG version is this, and
what's your sort_mem setting?

            regards, tom lane