Re: Decyphering LMT space bitmap

There's a funny thing about the:

    | Tail portion of Bitmap Blocks M blocks

It doesn't really exist despite Oracle documents to the contrary. Try creating a file with some waste space at the end of it so that the 'Tail' points to the start of the waste space; then increase the file size by one extent.

The 'Tail' will apparently move.

A potentially important detail for using LMTs (with uniform space management) - the file size should be a multiple of the extent size plus 64K (or in special cases, perhaps 128K is needed) to avoid wasting the best part of one extent at the end of the file.

Jonathan Lewis
http://www.jlcomp.demon.co.uk

Host to The Co-Operative Oracle Users' FAQ http://www.jlcomp.demon.co.uk/faq/ind_faq.html

Author of:
Practical Oracle 8i: Building Efficient Databases

-----Original Message-----
To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com> Date: 08 April 2002 21:52

|From the 'Data Management and Storage Internal" notes,
|
|Bitmapped Tablespace File Structure
|
|A new bitmapped tablespace file has the following structure:
|File Header 1 block
|Bitmapped File Space Header 1 block
|Head portion of of Bitmap Blocks N blocks
|Useful file blocks U units (A unit is a number
|of blocks)
|Tail portion of Bitmap Blocks M blocks
|

-- 
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-- 
Author: Jonathan Lewis
  INET: jonathan_at_jlcomp.demon.co.uk

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