Anton Maksimenkov <engineer@xxxxxxxxxxx> writes: > Second idea was to try to SELECT (user, cookie) pair and then UPDATE > it if it exists or INSERT if not. I has thought that if UPDATE will > rewrite same place in file with new count it may lead to more compact > table (file not grow and information about actual rows in file will > not changed). You're wasting your time, because Postgres doesn't work that way. UPDATE is really indistinguishable from DELETE+INSERT, and there will always be a dead row afterwards, because under MVCC rules both versions of the row have to be left in the table for some time after your transaction commits. See http://www.postgresql.org/docs/8.1/static/mvcc.html regards, tom lane
