Re: random_page_costs - are defaults of 4.0 realistic for SCSI RAID 1

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Decibel! wrote:
On Mon, Sep 10, 2007 at 06:22:06PM -0400, Mark Mielke wrote:
  
In my case, I set effective_cache_size to 25% of the RAM available to 
the system (256 Mbytes), for a database that was about 100 Mbytes or 
less. I found performance to increase when reducing random_page_cost 
from 4.0 to 3.0.
    
Just for the record, effective_cache_size of 25% is *way* too low in
most cases, though if you only have 1GB setting it to 500MB probably
isn't too far off.

Generally, I'll set this to however much memory is in the server, minus
1G for the OS, unless there's less than 4G of total memory in which case
I subtract less.
  
Agree. My point was only that there are conflicting database requirements, and that one setting may not be valid for both. The default should be whatever is the most useful for the most number of people. People who fall into one of the two extremes should know enough to set the value based on actual performance measurements.

Cheers,
mark

-- 
Mark Mielke <mark@xxxxxxxxx>

[Postgresql General]     [Postgresql PHP]     [PHP Users]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Yosemite]

  Powered by Linux