Re: Extent map block

Thank you Jonathan for the reply. On a database with 8k block size, it takes only 4 blocks. Is it not? I am trying to avoid having to worry about extent sizing altogether. That is, all user tablespaces I create will be locally managed tablespaces with uniform extent size of say 256k. Any segment of size, say, upto 25 GB will use these tablespaces. Only in special cases where a segment is going to be over 25GB I will create a tablespace with bigger extent size. What will be the impact of such a scheme? If 1GB segment requires only 32k then 10GB will require only 320K of extent map block space. If these blocks are cached then performance won't be impacted even for a full table scan. As the oracle allocates the new extents efficiently from the bitmaps stored in 64k block in the beginning of each datafile, having many extents should not be a problem. Can you comment on this? Thank you.

raghuvir

In article <973805040.12216.0.nnrp-04.9e984b29_at_news.demon.co.uk>,   "Jonathan Lewis" <jonathan_at_jlcomp.demon.co.uk> wrote:
>
> 1Gb at 64K needs about 32K of map.
>
> --
>
> Jonathan Lewis
> Yet another Oracle-related web site: http://www.jlcomp.demon.co.uk
>
> Practical Oracle 8i: Building Efficient Databases
>
> Publishers: Addison Wesley Longman
> Book bound date: 8th Dec 2000
> See a first review at:
> http://www.ixora.com.au/resources/index.htm#practical_8i
>
> cust102_at_my-deja.com wrote in message <8uf21u$ea8$1_at_nnrp1.deja.com>...
> >Hi,
> > Does anyone know how many extents can an extent map block cover?
 For
> >a locally managed tablespace with uniform extent size of 64k how many
> >extent map blocks are needed for 1GB segment?
> >
> >
> >raghuvir
> >
> >
> >
> >Sent via Deja.com http://www.deja.com/
> >Before you buy.
>
>

Sent via Deja.com http://www.deja.com/
Before you buy. Received on Thu Nov 09 2000 - 17:18:28 CST