On Thu, May 18, 2006 at 11:34:51AM +0100, Simon Riggs wrote: > On Tue, 2006-05-16 at 15:42 -0500, Jim C. Nasby wrote: > > On Tue, May 16, 2006 at 12:31:07PM -0500, Jim C. Nasby wrote: > > > In any case, my curiousity is aroused, so I'm currently benchmarking > > > pgbench on both a compressed and uncompressed $PGDATA/base. I'll also do > > > some benchmarks with pg_tmp compressed. > > > > Results: http://jim.nasby.net/bench.log > > > > As expected, compressing $PGDATA/base was a loss. But compressing > > pgsql_tmp and then doing some disk-based sorts did show an improvement, > > from 366.1 seconds to 317.3 seconds, an improvement of 13.3%. This is on > > a Windows XP laptop (Dell Latitude D600) with 512MB, so it's somewhat of > > a worst-case scenario. On the other hand, XP's compression algorithm > > appears to be pretty aggressive, as it cut the size of the on-disk sort > > file from almost 700MB to 82MB. There's probably gains to be had from a > > different compression algorithm. > > Can you re-run these tests using "SELECT aid FROM accounts ..." > "SELECT 1 ... " is of course highly compressible. > > I also note that the compressed file fits within memory and may not even > have been written out at all. That's good, but this sounds like the very > best case of what we can hope to achieve. We need to test a whole range > of cases to see if it is generally applicable, or only in certain cases > - and if so which ones. > > Would you be able to write up some extensive testing of Martijn's patch? > He's followed through on your idea and written it (on -patches now...)
Yes, I'm working on that. I'd rather test his stuff than XP's compression anyway. -- Jim C. Nasby, Sr. Engineering Consultant [EMAIL PROTECTED] Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461 ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
