Re: 8.4 open item: copy performance regression?

Robert Haas <robertmhaas@gmail.com> writes:
> It would be interesting to see some gprof or oprofile output from that
> test.   I went back and dug up the results that I got when I profiled
> this patch during initial development, and my version of the patch
> applied, the profile looked like this on my system:

Were you testing with a temp table?  The lack of XLogInsert in your
profile is striking.  Stefan's results upthread had it at the top,
and I got more or less the same thing here (didn't keep my numbers
unfortunately).

> Simon had the idea of further improving performance by keeping the
> current buffer locked (this patch just kept it pinned, but not
> locked), but I didn't see an obvious clean design for that.

The potential for deadlock seems sufficient reason not to do that.
        regards, tom lane