Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> "Todd A. Cook" <tcook(at)blackducksoftware(dot)com> writes:
>> I've noticed that on 8.4.0, commits can take a long time when a
>> temp table is repeatedly filled and truncated within a loop.
> The commit time doesn't seem tremendously out of line, but it looks
> like there's something O(N^2)-ish in the function execution. Do
> you see a similar pattern? With so many temp files there could well
> be some blame on the kernel side. (This is a Fedora 10 box.)
This sounds very similar to my experience here:
http://archives.postgresql.org/pgsql-hackers/2008-11/msg01472.php
Depending on what sort of RAID controller caching is present, a BBU
cache might be containing the problem up to some threshold. Perhaps
it's not so much O(N^2) as O(N)-<someconstant>, with a min of zero?
-Kevin