estimation of table size in oracle 9i

Please advice how to estimate in advance phisycal size of table in 9i or give a reference on dbf (oracle data file) format. I tried to test some scenarios but I got quite confused cause even for number fields size of table in bytes (measured by dba_extents) depends on values in fields
For example if I create table

create table t_num (t number,t1 number,t2 number,t3 number)

and insert 1048576 of records

insert into t_num values (1078,2000,3001,238)

table size is 24 117 248

if I'm inserting same number of records (definitely I dropping table & create it again before experiment)

insert into t_num values (1077,2001,3002,237)

table size is 25 427 968

how this can be explained? Received on Sat Jun 23 2007 - 11:19:13 CDT