Difference between Create Index without and with Parallel Clause

Question

Hi all.
I want to know the difference between Create Index with Parallel clause and Create Index without Parallel clause.
Any documentation.
Thanks,
Hassan

Answer 1

Sure?
dimitri@VDB> create table t parallel 3 as select * from all_objects;
Table created.
dimitri@VDB> set autotrace traceonly
dimitri@VDB> select * from t;
40934 rows selected.
Execution Plan
Plan hash value: 3050126167
| Id  | Operation            | Name     | Rows  | Bytes | Cost (%CPU)| Time     |    TQ  |IN-OUT| PQ Distrib |
|   0 | SELECT STATEMENT     |          | 40601 |  5075K|    50   (0)| 00:00:01 |        |      |            |
|   1 |  PX COORDINATOR      |          |       |       |            |          |        |      |            |
|   2 |   PX SEND QC (RANDOM)| :TQ10000 | 40601 |  5075K|    50   (0)| 00:00:01 |  Q1,00 | P->S | QC (RAND)  |
|   3 |    PX BLOCK ITERATOR |          | 40601 |  5075K|    50   (0)| 00:00:01 |  Q1,00 | PCWC |            |
|   4 |     TABLE ACCESS FULL| T        | 40601 |  5075K|    50   (0)| 00:00:01 |  Q1,00 | PCWP |            |
--------------------------------------------------------------------------------------------------------------Looks like PQ to me.
alter table t noparallel;
Table altered.
dimitri@VDB> select * from t;
40934 rows selected.
Execution Plan
Plan hash value: 1601196873
| Id  | Operation         | Name | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT  |      | 40601 |  5075K|   135   (1)| 00:00:02 |
|   1 |  TABLE ACCESS FULL| T    | 40601 |  5075K|   135   (1)| 00:00:02 |
--------------------------------------------------------------------------Same if we use an Index:
dimitri@VDB> create index t_idx on t(object_name) parallel 3;
Index created.
dimitri@VDB> select object_name from t;
40934 rows selected.
Execution Plan
Plan hash value: 4278805225
| Id  | Operation               | Name     | Rows  | Bytes | Cost (%CPU)| Time     |    TQ  |IN-OUT| PQ Distrib |
|   0 | SELECT STATEMENT        |          | 40601 |   674K|    50   (0)| 00:00:01 |        |      |            |
|   1 |  PX COORDINATOR         |          |       |       |            |          |        |      |            |
|   2 |   PX SEND QC (RANDOM)   | :TQ10000 | 40601 |   674K|    50   (0)| 00:00:01 |  Q1,00 | P->S | QC (RAND)  |
|   3 |    PX BLOCK ITERATOR    |          | 40601 |   674K|    50   (0)| 00:00:01 |  Q1,00 | PCWC |            |
|   4 |     INDEX FAST FULL SCAN| T_IDX    | 40601 |   674K|    50   (0)| 00:00:01 |  Q1,00 | PCWP |            |
-----------------------------------------------------------------------------------------------------------------Everything done on a single CPU (also only one core in the CPU) AMD Box.
Dim