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Rene Nyffenegger wrote:
>
> Hi
>
> Because of another thread in this NG, I wanted to find out
> about locally managed tablespaces. The key phrase I found is:
>
> Locally managed tablespaces track all extent information in the tablespace
> itself, using bitmaps, resulting in the following benefits:
> <list of benefits, many starting with improved...>
>
> What does it mean, the extent information is in the tablespace itself.
> Where is it stored in dictionary managed tablespaces? What is the
> extent information anyway?
>
> Tnx
>
> Rene
>
> --
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By default two tables hold all the bits and pieces (UET$, FET$) being a list of used and free extents respectively. Obviously as you add/remove extents, these tables have to be updated. Similarly if you coalesce then these tables could be updated. What you quickly end up with if you're going hard on the extent (de)allocation, is a bottleneck.
A locally managed tablespace plonks this information in a bitmap in each file, thus removing the contention point. I consider dictionary managed tablespace to be virtually obsolete..
hth
connor
-- ============================== Connor McDonald http://www.oracledba.co.uk "Some days you're the pigeon, some days you're the statue..."Received on Wed Aug 08 2001 - 12:51:54 CDT