oracle hint_no_parallel_no_parallel_index
oracle hint
1,no_parallel
1,适用于create 或alter开启表的并行,禁用其并行功能
1,no_parallel
1,适用于create 或alter开启表的并行,禁用其并行功能
SQL> create table t_parallel(a int) parallel 3;
表已创建。
SQL> explain plan for select a from t_parallel;
已解释。
SQL> select * from table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
Plan hash value: 2003410281
--------------------------------------------------------------------------------
--------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time
| TQ |IN-OUT| PQ Distrib |
| TQ |IN-OUT| PQ Distrib |
--------------------------------------------------------------------------------
--------------------------------
PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 13 | 2 (0)| 00:00:0
1 | | | |
| 1 | PX COORDINATOR | | | | |
| | | |
| | | |
| 2 | PX SEND QC (RANDOM)| :TQ10000 | 1 | 13 | 2 (0)| 00:00:0
1 | Q1,00 | P->S | QC (RAND) |
| 3 | PX BLOCK ITERATOR | | 1 | 13 | 2 (0)| 00:00:0
1 | Q1,00 | PCWC | |
PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
| 4 | TABLE ACCESS FULL| T_PARALLEL | 1 | 13 | 2 (0)| 00:00:0
1 | Q1,00 | PCWP | |
--------------------------------------------------------------------------------
--------------------------------
Note
-----
- dynamic sampling used for this statement (level=2)
已选择15行。
SQL> alter table t_parallel parallel 2;
表已更改。
SQL> explain plan for select a from t_parallel;
已解释。
SQL> select * from table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
Plan hash value: 2003410281
--------------------------------------------------------------------------------
--------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time
| TQ |IN-OUT| PQ Distrib |
| TQ |IN-OUT| PQ Distrib |
--------------------------------------------------------------------------------
--------------------------------
PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 13 | 2 (0)| 00:00:0
1 | | | |
| 1 | PX COORDINATOR | | | | |
| | | |
| | | |
| 2 | PX SEND QC (RANDOM)| :TQ10000 | 1 | 13 | 2 (0)| 00:00:0
1 | Q1,00 | P->S | QC (RAND) |
| 3 | PX BLOCK ITERATOR | | 1 | 13 | 2 (0)| 00:00:0
1 | Q1,00 | PCWC | |
PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
| 4 | TABLE ACCESS FULL| T_PARALLEL | 1 | 13 | 2 (0)| 00:00:0
1 | Q1,00 | PCWP | |
--------------------------------------------------------------------------------
--------------------------------
Note
-----
- dynamic sampling used for this statement (level=2)
已选择15行。
SQL>
SQL> explain plan for select /*+ no_parallel(t_parallel) */ a from t_parallel;
已解释。
SQL> select * from table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
Plan hash value: 1830942209
--------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 13 | 2 (0)| 00:00:01 |
| 1 | TABLE ACCESS FULL| T_PARALLEL | 1 | 13 | 2 (0)| 00:00:01 |
--------------------------------------------------------------------------------
Note
-----
PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
- dynamic sampling used for this statement (level=2)
已选择12行。
hint
no_parallel_index
1,同no_parallel,禁用create or alter索引的并行功能
no_parallel_index
1,同no_parallel,禁用create or alter索引的并行功能
来自 “ ITPUB博客 ” ，链接：https://blog.itpub.net/9240380/viewspace-751472/ ，如需转载，请注明出处，否则将追究法律责任。
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