Yes it could be,
if your application creates new rows and deletes 'old' ones then a rebuild will shrink the size.
If you have bitmaped indexes then they shrink too because they grow due to dml like update-stmt.
Thank-u for ur reply...in that case do u know if there's anyway to reduce the growth of tablespace other than resizing the tablespace??
any inputs appreciated
I don't see this as a problem. As you said that the size increases by 100M every month, that itself indicates that lots of data inserts is going on. And growth of tablespace due to valid inserts (important records) is what a database is expected to have.
Now the thing to watch here is are there lots of unused indexes.
if yes, then drop them because having unused indexes can lead to unwanted growth in tablespace.
And if you cannot avoid those lots of indexes then you need to rewrite your application querries in such a way that it least hampers your business logic and functionality and use mininimum indexes.
Amar "There is a difference between knowing the path and walking the path."