On 7/18/05, Tom Lane <[EMAIL PROTECTED]> wrote: > Christopher Petrilli <[EMAIL PROTECTED]> writes: > > http://blog.amber.org/diagrams/comparison_mysql_pgsql.png > > > Notice the VERY steep drop off. > > Hmm. Whatever that is, it's not checkpoint's fault. I would interpret > the regular upticks in the Postgres times (every several hundred > iterations) as being the effects of checkpoints. You could probably > smooth out those peaks some with appropriate hacking on bgwriter > parameters, but that's not the issue at hand (is it?).
I tried hacking that, turning it up to be more agressive, it got worse. Turned it down, it got worse :-) > I have no idea at all what's causing the sudden falloff in performance > after about 10000 iterations. COPY per se ought to be about a > constant-time operation, since APPEND is (or should be) constant-time. > What indexes, foreign keys, etc do you have on this table? What else > was going on at the time? The table has 15 columns, 5 indexes (character, inet and timestamp). No foreign keys. The only other thing running on the machine was the application actually DOING the benchmarking, written in Python (psycopg), but it was, according to top, using less than 1% of the CPU. It was just talking through a pipe to a psql prompt to do the COPY. Chris -- | Christopher Petrilli | [EMAIL PROTECTED] ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly