colease the tablespace

thanks in advance..

Colease tablespace detect free space between extents and merge small free space extents to create a large free extent. New free space (extent) if large enough will get use when new request for space allocation is issued.

I can't stress this enough:  Please read the docs before posting a question.  If after reading the docs, you still don't understand, we'll be happy to help you out.

excerpt from:
http://download-east.oracle.com/docs/cd/B19306_01/server.102/b14200/statements_3002.htm

COALESCE

For each datafile in the tablespace, this clause combines all contiguous free extents into larger contiguous extents.

In Dictionary Managed tablespaces (DMT), SMON process wakes up every 5 minutes for coalescing free space in DMTs. Optionally, the ALTER TABLESPACE <tablespace name> COALESCE command is also used to coalesce DMTs and reduce fragmentation.

On the other hand, Locally Managed Tablespaces (LMT) avoid recursive space management operations and automatically track adjacent free space, thus eliminating the need to coalesce free extents. This further reduces fragmentation.

ACTUALLY FRAGMENTATION MEANS?

You can see the meaning of Fragmentation in a dictionary.

http://www.m-w.com/dictionary/fragmentation