Re: UPDATE 66k rows too slow - Mailing list pgsql-performance

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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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