Re: BLCKSZ

Tom Lane wrote:
> Olleg Samoylov <olleg_s@mail.ru> writes:
>
>>I try to test this. Linux, memory page 4kb, disk page 4kb. I set BLCKSZ
>>to 4kb. I get some performance improve, but not big, may be because I
>>have 4Gb on test server (amd64).
>
> It's highly unlikely that reducing BLCKSZ is a good idea.  There are bad
> side-effects on the maximum index entry size, maximum number of tuple
> fields, etc.

Yes, when I set BLCKSZ=512, database dont' work. With BLCKSZ=1024
database very slow. (This was surprise me. I expect increase performance
in 8 times with 1024 BLCKSZ. :) ) As I already see in this maillist,
increase of  BLCKSZ reduce performace too. May be exist optimum value?
Theoretically BLCKSZ equal memory/disk page/block size may reduce
defragmentation drawback of memory and disk.

> In any case, when you didn't say *what* you tested, it's
> impossible to judge the usefulness of the change.
>             regards, tom lane

I test performace on database test server. This is copy of working
billing system to test new features and experiments. Test task was one
day traffic log. Average time of a one test was 260 minutes. Postgresql
7.4.8. Server dual Opteron 240, 4Gb RAM.

--
Olleg