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Home -> Community -> Mailing Lists -> Oracle-L -> Re: Decyphering LMT space bitmap
Hi Jeremiah,
>How is the LMT bitmap organized?
I did some research about the bitmap structure for an LMT tablespace a while ago.
The first 2 blocks are
Block 1 - For File Header
Block 2 - For File Space Bitmap Header
The bitmap itself is stored in 6 blocks after that , blocks 3 thru 8. Each of the bit tracks four extents represented by an F (hex for 15).
0000000000000000 0000000000000000 0000000000000000 00000000000000000
For eg: if you create a table with 1 extent
then there will be a 1 which 1 2 to the power of 0 = 1 and if there 2 extents then its 2^0 + 2^1 = 3
for 4 extents its 2^0+2^1+2^2+2^3 = 15 =F so the values will be either 0,1,3,7,or F for each bit.
In your case
FFFFFF3F00000000 0000000000000000 0000000000000000 00000000000000000there are 7 F's = 7*4 = 28 extents + 2 (represented by the 3) and = 30.
The rest are 0's because there is no data yet as there are only 30 extents. Each of these blocks 129024 extents.
When I did my test and I had raised the question at that time that the max data that can be stored is 129024 * 6 (blocks) = 774144 extents and if the extent size for argument is 1K then the max size the bitmap can track is 774144K or 7M data file. I have not found an answer yet.
You will find that there are about 504 lines of 64 bits each.
I have a detailed record of the test if you are interested that I can mail to you.
Hope this helps.
Regards,
See Dave Matthews Band live or win a signed guitar http://r.lycos.com/r/bmgfly_mail_dmb/http://win.ipromotions.com/lycos_020201/splash.asp
-- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Madhavan Amruthur INET: mad5698_at_lycos.com Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).Received on Mon Apr 08 2002 - 15:53:31 CDT
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