how to get the index size without creating the index on table?

There are multiple ways we can calculate the Index size without creating it.
1.just check the table size and based on the number of columns used on the index we may put the approx index size.
2.just take the explain plan for the index create statement ,it will show you the index size.

script to grant read/write access to user from all Db users in oracle database?

Here is the script which I used to pull all the grants and push to ROLE.
then grant to role to user.

select 'grant select ,update,insert,delete on '||owner||'.'||view_name||' to RW_ROLE;' from dba_views where owner in (select username from dba_users where username not in ('SYSTEM','DBSNMP','SYS','OUTLN','OLAPSYS','CTXSYS','EM_MONITOR','SYSMAN') );

select 'grant select ,update,insert,delete on '||owner||'.'||table_name||' to RW_ROLE;' from dba_tables where owner in (select username from dba_users where username not in ('SYSTEM','DBSNMP','SYS','OUTLN','OLAPSYS','CTXSYS','EM_MONITOR','SYSMAN') );