On Thu, Sep 01, 2005 at 02:47:06PM -0400, Tom Lane wrote: > Matthew Sackman <[EMAIL PROTECTED]> writes: > > Obviously, to me, this is a problem, I need these queries to be under a > > second to complete. Is this unreasonable? > > Yes. Pulling twenty thousand rows at random from a table isn't free.
I appreciate that. But I'm surprised by how un-free it seems to be. And it seems others here have performance I need on similar hardware. > You were pretty vague about your disk hardware, which makes me think > you didn't spend a lot of money on it ... and on low-ball hardware, > that sort of random access speed just isn't gonna happen. Well, this is a development box. But the live box wouldn't be much more than RAID 1 on SCSI 10ks so that should only be a halving of seek time, not the 1000 times reduction I'm after! In fact, now I think about it, I have been testing on a 2.4 kernel on a dual HT 3GHz Xeon with SCSI RAID array and the performance is only marginally better. > If the queries you need are very consistent, you might be able to get > some mileage out of CLUSTERing by the relevant index ... but the number > of indexes you've created makes me think that's not so ... No, the queries, whilst in just three distinct forms, will effectively be for fairly random values. Matthew ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend