INDEX FAST FULL SCAN 也无法开并行

SQL> drop table t1 purge ;

表已删除。

SQL> create table t1 as select * from dba_objects;

表已创建。

SQL> insert into t1 select * from t1;

已创建72665行。

SQL> /

已创建145330行。

SQL> commit;

提交完成。

SQL> create index t_idx2 on t1(owner,object_name,status) nologging;

索引已创建。

SQL> select owner,object_name from t1 a where status='INVALID';

已选择16行。


执行计划
----------------------------------------------------------
Plan hash value: 2575195509

-------------------------------------------------------------------------------
| Id  | Operation	     | Name   | Rows  | Bytes | Cost (%CPU)| Time     |
-------------------------------------------------------------------------------
|   0 | SELECT STATEMENT     |	      |   145K|  5411K|   412	(1)| 00:00:05 |
|*  1 |  INDEX FAST FULL SCAN| T_IDX2 |   145K|  5411K|   412	(1)| 00:00:05 |
-------------------------------------------------------------------------------

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

   1 - filter("STATUS"='INVALID')


统计信息
----------------------------------------------------------
	  1  recursive calls
	  0  db block gets
       1938  consistent gets
	  0  physical reads
	  0  redo size
	744  bytes sent via SQL*Net to client
	426  bytes received via SQL*Net from client
	  3  SQL*Net roundtrips to/from client
	  0  sorts (memory)
	  0  sorts (disk)
	 16  rows processed

SQL> 


SQL> select /*+ parallel(a 4)*/ owner,object_name from t1 a where status='INVALID';

已选择16行。


执行计划
----------------------------------------------------------
Plan hash value: 2494645258

--------------------------------------------------------------------------------------------------------------
| Id  | Operation	     | Name	| Rows	| Bytes | Cost (%CPU)| Time	|    TQ  |IN-OUT| PQ Distrib |
--------------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT     |		|   145K|  5411K|   252   (1)| 00:00:04 |	 |	|	     |
|   1 |  PX COORDINATOR      |		|	|	|	     |		|	 |	|	     |
|   2 |   PX SEND QC (RANDOM)| :TQ10000 |   145K|  5411K|   252   (1)| 00:00:04 |  Q1,00 | P->S | QC (RAND)  |
|   3 |    PX BLOCK ITERATOR |		|   145K|  5411K|   252   (1)| 00:00:04 |  Q1,00 | PCWC |	     |
|*  4 |     TABLE ACCESS FULL| T1	|   145K|  5411K|   252   (1)| 00:00:04 |  Q1,00 | PCWP |	     |
--------------------------------------------------------------------------------------------------------------

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

   4 - filter("STATUS"='INVALID')


统计信息
----------------------------------------------------------
	 12  recursive calls
	  0  db block gets
       4256  consistent gets
       4125  physical reads
	  0  redo size
	871  bytes sent via SQL*Net to client
	426  bytes received via SQL*Net from client
	  3  SQL*Net roundtrips to/from client
	  0  sorts (memory)
	  0  sorts (disk)
	 16  rows processed


INDEX FAST FULL SCAN 多快读 也无法走并行