Re: Longer and longer updates

* Steve Wilmarth <swilmarth@eknow.com> [010205 12:50] wrote:
>
> Hi all-
>
> In doing some stress testing I noticed that our database was slowing
> down significantly after doing the same update repeatedly on a table
> with no indexes, so I tried this:
>
> 1) created an empty database
>
> 2) made a simple table with a single row:
>
>    create table test (key int4, data int4);
>    insert into test values (1, 0);
>
> 3) executed this statement tons of times:
>
>    update test set data=1234 where key=1
>
> Here are the results -- it's pretty discouraging, I hope I'm making some
> simple mistake, or maybe this is expected behavior for some reason?
>
> After this many updates        ...it took this long for 1000 more updates
> -----------------------        ------------------------------------------
>         0                                   10880 ms
>       5,000                                 10549 ms
>      10,000                                 17380 ms
>      15,000                                 20040 ms
>      20,000                                 20060 ms
>      25,000                                 20589 ms
>      30,000                                 30749 ms
>      35,000                                 30350 ms
>      40,000                                 30910 ms
>      45,000                                 37570 ms
>      50,000                                 40379 ms
>
> This seems to be independent of starting and stopping my client and the
> postmaster, running vacuum, praying, etc.  I'm on RedHat6.2
> running with the 7.1beta4 rpms.
>
> Anyone know what's going on here?

You're not vacuuming.

--
-Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org]
"I have the heart of a child; I keep it in a jar on my desk."