Gabriel, On 3/27/06 5:34 AM, "Gábriel Ákos" <akos.gabriel@xxxxxxxxxx> wrote: > Question: I have a table with 2.5M rows. count(*) on this table is > running 4 minutes long. (dual opteron, 4gig ram, db on 4 disk raid10 > array (sata, not scsi)) Is this normal? How could I make it run faster? > Maybe make it run faster for the 2nd time? Which parameters should I > change in postgresql.conf and how? Before changing anything with your Postgres configuration, you should check your hard drive array performance. All select count(*) does is a sequential scan of your data, and if the table is larger than memory, or if it's the first time you've scanned it, it is limited by your disk speed. To test your disk speed, use the following commands and report the times here: time bash -c "dd if=/dev/zero of=bigfile bs=8k count=500000 && sync" time dd if=bigfile of=/dev/null bs=8k If these are taking a long time, from another session watch the I/O rate with "vmstat 1" for a while and report that here. - Luke
