Re: x206-x225

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От Richard Huxton
Тема Re: x206-x225
Дата
Msg-id 441181C6.3040401@archonet.com
обсуждение исходный текст
Ответ на x206-x225  ("H.J. Sanders" <hjs@rmax.nl>)
Ответы Re: x206-x225
Re: x206-x225
Список pgsql-performance
H.J. Sanders wrote:
> X206                                       IBM X226
> ----------------------                            -------------------
> processor                        Pentium 4 3.2
> Ghz                            Xeon 3.0 Ghz
> main memory                    1.25
> GB                                        4 GB
> discs                              2 x SCSI RAID1  10000RPM
> 1 x ATA 7200 RPM

Noting that the SCSI discs are on the *slower* machine.

> Time at X206            Time at X226
> --------------------        ------------------
> insert record (1 to 10000)          6 sec.    41 sec.
> select record (1 to 10000)          4          4
> delete record (1 to 10000)          6         41
>
>
> This is ofcourse a totally unexpected results (you should think off the
> opposite).

Your ATA disk is lying about disk caching being turned off. Assuming
each insert is in a separate transaction, then it's not going to do
10,000 / 6 = 1667 transactions/sec - that's faster than it's rotational
speed.

> Funny is that the select time is the same for both machines.

Because you're limited by the speed to read from RAM.

By the way - these sort of tests are pretty much meaningless in any
practical terms.
--
   Richard Huxton
   Archonet Ltd

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