Simple index (How to view data(all columns) of an index in toad)

Question

Hi All,
I am training myself on sql tuning and over the years I have seen ppl creating many indexes, today I am trying to learn various types of indexes and just curious to see physical data in an index but I am not able to do so on toad, I know if I have some index def like:
create index employees_employee_id on employees(employee_id)
my index would have two columns of information : first rowid and employee_ids in sorted order, right ? <- if my understanding is not right could any1 please correct me here.
PS: The major problem is to see physical index data in toad, please help me with it.
Many thanks
Rahul

Answer 1

There is no SELECT query that could be written over an index. But a SELECT query on a TABLE can be in such a way that Oracle only scans the index and give you the information
Here is an example.
SQL> create table t
  2  (
  3    no integer
  4  );
Table created.
SQL> create index t_idx on t(no);
Index created.
SQL> insert into t       
  2  select level
  3    from dual connect by level <= 10;
10 rows created.
SQL> commit;
Commit complete.
SQL> alter table t modify no not null;
Table altered.
SQL> exec dbms_stats.gather_table_stats(user, 'T', cascade=>true)
PL/SQL procedure successfully completed.
SQL> select rowid, no from t;
ROWID                      NO
AAFrZaABMAAAiKKAAA          1
AAFrZaABMAAAiKKAAB          2
AAFrZaABMAAAiKKAAC          3
AAFrZaABMAAAiKKAAD          4
AAFrZaABMAAAiKKAAE          5
AAFrZaABMAAAiKKAAF          6
AAFrZaABMAAAiKKAAG          7
AAFrZaABMAAAiKKAAH          8
AAFrZaABMAAAiKKAAI          9
AAFrZaABMAAAiKKAAJ         10
10 rows selected.
SQL> select * from table(dbms_xplan.display_cursor);
PLAN_TABLE_OUTPUT
SQL_ID  35mwb1b3fpfrh, child number 0
select rowid, no from t
Plan hash value: 3354442786
| Id  | Operation        | Name  | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT |       |       |       |     1 (100)|          |
|   1 |  INDEX FULL SCAN | T_IDX |    10 |    30 |     1   (0)| 00:00:01 |
13 rows selected.
Actually in this case i have queried the INDEX