Re: Postgresql update op is very very slow

On Jun 24, 2008, at 9:12 PM, jay wrote:

>
> I've a table with about 34601755 rows ,when I execute 'update
> msg_table set
> type=0;' is very very slow, cost several hours, but still not
> complete?
>
> Why postgresql is so slowly? Is the PG MVCC problem?
>
> But I try it on Mysql, the same table and rows, it only cost about 340
> seconds.
>
> Any idea for the problem?
>
>
> My machine config:
>     Memory 8G, 8 piece 15K disk , 2CPU(Quad-Core) AMD
>     OS: Red Hat AS4
>
> My postgres.conf main parameter is following:
>
>

Hi Jay,

Is the "type" used in an index?  Have you properly increased your
number of checkpoint segments?  Any warnings in in your log file about
excessive checkpointing?

Cheers,

Rusty
--
Rusty Conover
InfoGears Inc.
http://www.infogears.com