Tablespace

hi everyone

in oracle8i administrators guide it is stated

" Beginning with Oracle8i, you can now create locally managed tablespaces,
which use bitmaps (instead of SQL dictionary tables) to track used and free space."

here, i don't understand the term "bitmaps" .
can anyone explain me about "bitmaps" pls...

regards

Valsaraj

Each bit in the bitmap corresponds to a block or a group of blocks. When an extent is allocated or freed for reuse, Oracle changes the bitmap values to show the new status of the blocks.

This extract is from the link below

http://www.dbasupport.com/oracle/ora8/page11.shtml

thanks topstar..

now i assume, bitmaps is the location ( basically a map itself) keeping the track of extens. each extent is recorded as a bit in bitmap ! so howmany bits, that much extens.. right ???

thanks anyway...

regards

valsaraj