On Tue, Apr 22, 2008 at 2:59 PM, David Wilson <david.t.wilson@xxxxxxxxx> wrote: > On Tue, Apr 22, 2008 at 4:38 PM, Scott Marlowe <scott.marlowe@xxxxxxxxx> wrote: > > The best bet is to issue an "analyze table" (with your table name in > > there, of course) and see if that helps. Quite often the real issue > > is that pgsql is using a method to insert rows when you have 10million > > of them that made perfect sense when you had 100 rows, but no longer > > is the best way. > > > > This has caused the behavior to be... erratic. That is, individual > copies are now taking anywhere from 2 seconds (great!) to 30+ seconds > (back where we were before). I also clearly can't ANALYZE the table > after every 4k batch; even if that resulted in 2 second copies, the > analyze would take up as much time as the copy otherwise would have > been. I could conceivably analyze after every ~80k (the next larger > unit of batching; I'd love to be able to batch the copies at that > level but dependencies ensure that I can't), but it seems odd to have > to analyze so often. Normally, after the first 50,000 or so the plan won't likely change due to a new analyze, so you could probably just analyze after 50k or so and get the same performance. If the problem is a bad plan for the inserts / copies. also, non-indexed foreign keyed fields can cause this problem.
