Re: Improving N-Distinct estimation by ANALYZE

FWIW, results from a FBSD6.0 box. Between every run I ran code to zero
800MB (out of 1G) of memory, which should have effectively flushed the
OS cache (it would just put the OS into swapping).

Reading 1% (1280/128000 blocks 1048576000 bytes) total time 6870595us
MB/s 1.53 effective MB/s 152.62
Reading 2% (2560/128000 blocks 1048576000 bytes) total time 13397833us
MB/s 1.57 effective MB/s 78.26
Reading 3% (3840/128000 blocks 1048576000 bytes) total time 16288218us
MB/s 1.93 effective MB/s 64.38
Reading 4% (5120/128000 blocks 1048576000 bytes) total time 17998334us
MB/s 2.33 effective MB/s 58.26
Reading 5% (6400/128000 blocks 1048576000 bytes) total time 22958791us
MB/s 2.28 effective MB/s 45.67
Reading 6% (7680/128000 blocks 1048576000 bytes) total time 21272511us
MB/s 2.96 effective MB/s 49.29
Reading 7% (8960/128000 blocks 1048576000 bytes) total time 21708130us
MB/s 3.38 effective MB/s 48.30
Reading 8% (10240/128000 blocks 1048576000 bytes) total time 23213377us
MB/s 3.61 effective MB/s 45.17
Reading 9% (11520/128000 blocks 1048576000 bytes) total time 33641027us
MB/s 2.81 effective MB/s 31.17
Reading 10% (12800/128000 blocks 1048576000 bytes) total time 22484234us
MB/s 4.66 effective MB/s 46.64
Reading 15% (19200/128000 blocks 1048576000 bytes) total time 23985072us
MB/s 6.56 effective MB/s 43.72
Reading 20% (25600/128000 blocks 1048576000 bytes) total time 26332888us
MB/s 7.96 effective MB/s 39.82
--
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