Robert Haas <robertmhaas@gmail.com> writes:
> On Mon, Apr 25, 2011 at 5:45 PM, Andres Freund <andres@anarazel.de> wrote:
>> [ lots of awesome test results ]
> Very interesting work. I think it's interesting that there is so much
> allocation happening inside MessageContext; I barely knew that
> existed, let alone that it was a hotspot for memory allocation.
The reason it shows as a hotspot is that parsing and planning happen in
that context for the simple-Query code path. You'd get different
answers if you were using extended-query protocol, or running prepared
statements, or doing the bulk of your work in plpgsql, etc etc.
It would be interesting if Andres could dig down another level or so in
the call stack to see where the list creations etc are called from, but
I'll bet quite a bit that what we're looking at is mostly parse/plan
activity. (The high showing of bitmapset activity is a dead tipoff for
planner, in particular, since that datatype is hardly used at all
elsewhere.)
regards, tom lane