Re: Table-Extents / Performance
Date: Tue, 11 Sep 2001 10:38:58 GMT
Message-ID: <6Rln7.43$vr1.6352_at_typhoon.jacksonville.mediaone.net>
"waltervdv" <marcus.kuehl_at_t-online.de> wrote in message
news:b2677297.0109110152.64cd8786_at_posting.google.com...
> Hallo !
>
> Recently I read in a paper that it's no problem to have tables with
> many extents in a database
> (http://technet.oracle.com/deploy/availability/pdf/defrag.pdf). My
> DBA-Handbook says, it is the best to put the whole table into one
> extent.
>
> I'm working on a database with no online-transactions - only
> batch-jobs (inserts and deletes, very few updates). Last week I had to
> remove the data from some tables. I did that by "delete from table
> xxxx". It was a hard job, because it took very very long.
> Afterwords I looked at some tables with the schema-browser of toad.
> Although the tables where empty it took very long (maybe 20 seconds)
> for toad to show the table-data-view. The tables had some extents
> (maybe 10 - 30).
> After I had done a "truncate table xxx drop storage" the access-speed
> to these tables was "normal" again (1 - 2 seconds).
> I think this is because the tables had only one extent left after the
> truncate statement.
> So why can anybody say that the number of extents is not important for
> performance ?
>
> Any Ideas ????
>
> Marcus
Received on Tue Sep 11 2001 - 12:38:58 CEST