Re: Bitmap Heap scan 8.1/8.2

Alvaro Herrera wrote:
>
> It's an arbitrary number, based on which all the other numbers are
> measured.

Now that I read more intensively he docs I see that all the cost
parameters are related one with the other.

> What people generally do around here is mess with random_page_cost, and
> leave seq_page_cost alone.  Often, it's the ratio
> seq_page_cost/random_page_cost what's most important to the cost
> equations results.  (seq_page_cost wasn't tunable at all until
> recently, say 8.1 or 8.2 AFAIR).

Ok, now the 8.1 server has a RAID1 hardware board with SCSI disks, and
the 8.2 is just a PentiumD with SATA disks (it's my desktop PC where I
do tests). Should I have a lower random_page_cost on a machine that is
likely to have a lower disk IO speed?

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