Re: Compression and on-disk sorting

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.

> Does anyone have time to hack some kind of compression into the on-disk
> sort code just to get some benchmark numbers? Unfortunately, doing so is
> beyond my meager C abilitiy...
--
Jim C. Nasby, Sr. Engineering Consultant jnasby(at)pervasive(dot)com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461