Sean Chen <zyschen@xxxxxxxxx> wrote: > Now from what you mentioned below, do you know what's the cost of > postgres requesting new disk space from OS? Depending on your OS and its version, your file system, your mount options, and your disk subsystem (and its firmware revision), there could be various effects -- the one likely to be biting you is write barriers. When you allocate additional space from the OS, and it extends a file or creates a new file, there might be a write barrier to ensure that the file system catalog entries are persisted. This could cause all writes (and possibly even reads) to pause until the data is written to disk. That's just a guess, of course. If you have a profiler you can run you might be able to pin it down with that. -Kevin -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
