Hannu,
On 10/3/05 2:43 PM, "Hannu Krosing" <[EMAIL PROTECTED]> wrote:
> Just FYI, I run a count(*) on a 15.6GB table on a lightly loaded db and
> it run in 163 sec. (Dual opteron 2.6GHz, 6GB RAM, 6 x 74GB 15k disks in
> RAID10, reiserfs). A little less than 100MB sec.
This confirms our findings - sequential scan is CPU limited at about 120MB/s
per single threaded executor. This is too slow for fast file systems like
we're discussing here.
Bizgres MPP gets 250MB/s by running multiple scanners, but we still chew up
unnecessary amounts of CPU.
> After this I ran count(*) over a 2.4GB file from another tablespace on
> another device (4x142GB 10k disks in RAID10) and it run 22.5 sec on
> first run and 12.5 on second.
You're getting caching effects here.
- Luke
---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
