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I have been struggling to find the right answer to the question: What is
the bitmap header size for a uniform extents LMT? 64K, 1 block, 2
blocks????
I find one note on Metalink (Note: 111666.1) that says its 64K .
Mr.Jonathan Lewis says " A quirky little detail about bitmap sizes also came up recently on the Oracle-L mailing list. If you define a very small tablespace - in this context 'very small' means something between 5 blocks and '64K plus one extent' then Oracle will give you a bitmap of just one block - which still allows you to grow the file quite comfortably, of course."
Then another example on Metalink (Note: 109630.1) which goes:
SQL> create tablespace mult 2 datafile '/oracle2/OFA_base/u02/oradata/V816/mult1.dbf' size 100k, 3 '/oracle2/OFA_base/u02/oradata/V816/mult2.dbf' size 100k 4 extent management local uniform size 50K; Tablespace created. SQL> select tablespace_name,file_id,block_id,blocks 2 from dba_free_space 3 where tablespace_name='MULT' ; TABLESPACE_NAME FILE_ID BLOCK_ID BLOCKS ------------------------------ ---------- ---------- ---------- MULT 15 4 25 MULT 16 4 25 BLOCK_ID=4 : In an ordinary datafile, the first block where to store data is block 2. Therefore, two more blocks are reserved for the header bitmap of the locally managed datafile. BLOCKS=25 : The datafile has a size of 100K which equals 50 blocks in this database => There are only 25 blocks (local uniform size 50K)left for data starting at block n°4, then 22 blocks are unused.
=> Header bitmap = 2 blocks for each datafile
Moi Confused. Whats the definite word on this? Should be something like if the datafile size is x, then its n, else its some other number.
Thanks
Raj
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