Vinit,

By system table space I actually tried to mean default tablespace only as in my case my default tablespace is system.

It is always better to have a seperate tablespace for creating temporary tables which are going to get frequently created and dropped. This operation will cause database fragmentation.To confine this database fragmentation we would like to go for a seperate tablespace for these temporary tables.

Now I would like to ask the same question with a bit more elaboration.

Suppose I know that the temporary tables that are going to get created can have at max 50 columns ,min 3 cols, max 100000 rows min 0 rows.
Now for such a table we are opting for a seperate tablespace altogether.
Now to create the tablespace I would issue something like the following query

create tablespace XXX datafile
'YYY' size 850M reuse
default storage (
initial 1M
next 1M
MINEXTENTS 1 MAXEXTENTS UNLIMITED
pctincrease 0);

Now what I need to know is how can I calculate the size (like 850M in the above query) of the datafile to be created for the Tablespace.