Re: [HACKERS] 8K block limit

Tatsuo Ishii wrote:
>
> But modern Unixes have read/write ahead i/o if it seems a sequential
> access, don't they. I did some testing on my LinuxPPC box.
>
> 0. create table t2(i int,c char(4000));
> 1. time psql -c "copy t2 from '/tmp/aaa'" test
> (aaa has 5120 records and this will create 20MB table)
> 2. time psql -c "select count(*) from t2" test
> 3. total time of the regression test
>
> o result of testing 1
>
> 8K: 0.02user 0.04system 3:26.20elapsed
> 32K: 0.03user 0.06system 0:48.25elapsed
>
> 32K is 4 times faster than 8k!
>
> o result of testing 2
>
> 8K: 0.02user 0.04system 6:00.31elapsed
> 32K: 0.04user 0.02system 1:02.13elapsed
>
> 32K is neary 6 times faster than 8k!

Did you use the same -B for 8K and 32K ?
You should use 4x buffers in 8K case!

Vadim