bitmap indexes

hi guys,

how do u estimate the size of an bitmap index i.e the initial extent of it.
ex: cust table --- 350000 recoreds
index column --- marital_status varchar2(1)

so,what should be the initial size of the index...
any sites or links available regarding this....

thanx

Replace the proper schema name in the code below and rin it:

Code:

---

declare
tot_blocks number;
tot_bytes number;
unused_blocks number;
unused_bytes number;
lufid number;
lubid number;
lub number;
begin
dbms_space.unused_space(
'REPLACE_ME_WITH_THE_SCHEMA_NAME',
'marital_status','INDEX',
tot_blocks,
tot_bytes,
unused_blocks,
unused_bytes,
lufid,
lubid,
lub);
dbms_output.put_line('total_blocks :'||tot_blocks);
dbms_output.put_line('total_bytes :'||tot_bytes);
dbms_output.put_line('unused_blocks :'||unused_blocks);
dbms_output.put_line(' The file ID of the last extent which contains data:'||lufid);
dbms_output.put_line(' The block ID of the last extent which contains data :'||lubid);
dbms_output.put_line(' The last block within this extent which contains data :'||lub);
end;
/

---

HI...JULIAN THANKX,

the script u have given works for an already existing index ,but in my case i am going to create the index for the first time...

Why don't you create the index first and then check the sizes....