Hannu Krosing: > did you also test this with fsync=off ? Yes. No significant difference. > I suspect that what you are seeing is the effect of randomly writing to > the index files. While sequential write performance can be up to > 80MB/sec on modern drives, sequential writes are an order of magnitude > slower. And at your data sizes you are very likely to hit a > CHECKPOINT, which needs to do some random writes. Yes, from the server log I noticed that I hit checkpoints too early and too often. I tried the astronomical value of 1000 for checkpoint_segments to not hit a single one for the whole test run (copying 800 MB) -- even though that is no good idea in practice of course. It took even longer then. Probably because the server created a lot of 16 MB log files (about 300 in my case) which is presumly more costy (at least for the first run?) than overwriting existing files. I am not too much into that, though, since this is not a solution anyway on the long run IMHO. Thanks again. Felix -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
