Re: Locally Managed Tablespaces

  • From: Wolfgang Breitling <breitliw@xxxxxxxxxxxxx>
  • To: niall.litchfield@xxxxxxxxx
  • Date: Thu, 20 Jan 2005 13:55:58 -0700

I too prefer uniform extent sizing, provided I have the freedom of 
grouping tables into different tablespace based on table size, and 
possibly other criteria, so that I do not end up with objects of vastly 
different size in the same tablespace. Then you are face with the 
dilemma of allocation a lot of empty space for small tables if you make 
the extent size largish, or with very many extents for large tables if 
you make the extent size smallish. As long as you are talking numbers of 
extents which are humanly comprehendable that latter part is not an 
inherent problem. Still, I like to keep the number of extents at a 3-4 
digit maximum.
Autoallocate gets you around that "problem". Of course, once you get 
into really large tables/indexes you ought to be looking at partitioning 
which also helps alleviate the problem. However, that requires EE plus 
extra $$ so may not be a solution for everyone.

Niall Litchfield wrote:

> On Thu, 20 Jan 2005 15:12:25 -0500, Subbiah, Nagarajan
> <Nagarajan.Subbiah@xxxxxxxx> wrote:
>>Is the Uniform allocation has any advantageous than SYSTEM allocation type?
>>Does the SYSTEM allocation type has any issues?
> With uniform allocation you cannot get free space fragmentation
> problems, with system managed you can (but are unlikely to).
> With uniform allocation if you guess^H^H^H^H calculate the segment
> size wrongly you can end up with very large or very small numbers of
> extents.
> I prefer and have long advocated uniform extent sizing, others have
> advocated a system policy.


Wolfgang Breitling
Centrex Consulting Corporation

Other related posts: