sql analysis report and fbi

set lines 200 pages 999
col plan_table_output format a180
drop table t1 purge;
create table t1 (id integer, x varchar2(100));
insert into t1 select rownum, 'x' || mod(rownum, 500) from dual connect by level <= 50000;
create index t1_indx on t1(substr(x, 2, 3));
exec dbms_stats.gather_table_stats(null, 't1', method_opt=>'for all columns size 1');
exec dbms_stats.gather_table_stats(null, 't1', method_opt=>'for all hidden columns size 1');

set feedback only
select * from t1 where substr(x, 2, 3) = '123';

set feedback on
select * from table(dbms_xplan.display_cursor(null,null,format=>'typical'));

--

SQL_ID  azsfzfr3w3br1, child number 0
-------------------------------------
select * from t1 where substr(x, 2, 3) = '123'

Plan hash value: 3617692013

--------------------------------------------------------------------------
| Id  | Operation         | Name | Rows  | Bytes | Cost (%CPU)| Time     |
--------------------------------------------------------------------------
|   0 | SELECT STATEMENT  |      |       |       |    31 (100)|          |
|*  1 |  TABLE ACCESS FULL| T1   |   100 |  1400 |    31   (4)| 00:00:01 |
--------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   1 - filter(SUBSTR("X",2,3)='123')


18 rows selected.