How can I reclam the space

Question

oracle 10g, on the production one of the schema (40GB), i took export and restored one of the test env. and i see the datafie size 15GB.
question how can I reclam the space on production whitout any outage. can i able to do something online to reclame the space?
Thanks

Answer 1

What about Segment Space Management on your Tablespace of that table? ASSM(auto)/MSSM(manual)
MSSM:
- ALTER TABLE ... MOVE
alter table .. move - this makes your index unusable. You have to "alter index ... rebuild" after that
- ALTER INDEX ... REBUID
ASSM:
- ALTER TABLE ... SHRINK SPACE
You can shrink space online ... But You have "alter table ... enable row movement"
"alter table ... enable row movement" can make stored procedure depend on this table status be INVALID.
You can shrink space online, Ifr you have heavy DML, that can make your table blocking lock.
STEP SHOULD BE =>
ALTER TABLE ... ENABLE ROW MOVEMENT;
ALTER TABLE ... SHRINK SPACE COMPACT; -- THIS NOT AFFECT DML, BUT NOT REDUCR HWM
ALTER TABLE ... SHRINK SPACE; -- THIS HELP REDUCE HWM
http://download.oracle.com/docs/cd/B19306_01/server.102/b14231/schema.htm#ADMIN10161
- ALTER INDEX ... SHRINK SPACE
If your data is LOB, you have to "alter table ... move lob"
http://it.toolbox.com/blogs/surachart/move-lobsegment-to-different-tablespace-30530
Good Luck