Re: UPDATE 66k rows too slow

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От Miguel Arroz
Тема Re: UPDATE 66k rows too slow
Дата
Msg-id 4E25452D-B464-4D03-90AF-102501336158@guiamac.com
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Ответ на Re: UPDATE 66k rows too slow  ("Joshua D. Drake" <jd@commandprompt.com>)
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Hi!

   The disk subsystem will be a RAID 1, but for now it's just a single
7200 rpm 160 GB SATA hard drive. The PgSQL version is 8.3, the latest
one.

   I have done some performance tests on the drive, and it handles
about 40 MB/s on sequential writes, so I'm assuming it's OK.

   Yours

Miguel Arroz

On 2008/03/10, at 23:56, Joshua D. Drake wrote:

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> On Mon, 10 Mar 2008 23:46:10 +0000
> Miguel Arroz <arroz@guiamac.com> wrote:
>        tty             ad4              ad6             cpu
>>  tin tout  KB/t tps  MB/s   KB/t tps  MB/s  us ni sy in id
>>    0   60 33.48 449 14.66   0.00   0  0.00  11  0  3  0 86
>>    0  180 16.85 599  9.87   0.00   0  0.00   1  0  1  0 98
>>    0   60 55.37 455 24.58   0.00   0  0.00  25  0  4  1 69
>>    0   60 49.83 376 18.28   0.00   0  0.00  18  0  5  1 76
>>    0   60 29.86 363 10.58   0.00   0  0.00   3  0  0  1 96
>>    0   60 36.21 365 12.90   0.00   0  0.00  12  0  3  1 84
>>    0   60 33.13 353 11.41   0.00   0  0.00   2  0  2  0 96
>>    0   60 39.47 345 13.28   0.00   0  0.00  16  0  3  0 80
>>    0   60 40.48 363 14.34   0.00   0  0.00   8  0  2  0 89
>>    0   60 30.91 397 11.97   0.00   0  0.00   5  0  2  0 93
>>    0   60 18.21 604 10.75   0.00   0  0.00   5  0  2  0 93
>>    0   60 48.65 359 17.04   0.00   0  0.00  20  0  6  0 74
>>    0   60 32.91 375 12.04   0.00   0  0.00  10  0  4  0 86
>>    0   60 35.81 339 11.84   0.00   0  0.00   3  0  2  0 96
>>    0   60 33.38 394 12.83   0.00   0  0.00  11  0  4  0 85
>>    0   60 34.40 313 10.51   0.00   0  0.00   4  0  2  0 93
>>    0   60 45.65 358 15.94   0.00   0  0.00  19  0  7  0 74
>>    0   60 37.41 309 11.28   0.00   0  0.00   3  0  2  0 95
>>    0   60 32.61 447 14.22   0.00   0  0.00  10  0  3  1 86
>>    0   60 17.11 516  8.63   0.00   0  0.00   1  0  1  0 98
>>
>>   There's surely a lot of disk activity going on. With this
>> figures, I could have written some hundred gigabytes during the
>> query execution! Something is definitely not right here.
>
>
> Well the above says you are getting ~ 10-15MB/s a second performance.
> What is the disk subsystem you have. Also note that the duration
> probably went up because you didn't vacuum between tests.
>
> What version of PostgreSQL (I missed it).
>
> Joshua D. Drake
>
>
>
> - --
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Miguel Arroz
http://www.terminalapp.net
http://www.ipragma.com




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