Oracle 11g RAC跨例項控制並行
在Oracle 10g RAC中的並行執行是由兩個引數來控制的:instance_groups和parallel_instance_group這兩個引數在Oracle 10g RAC中必須同時設定。
instance_groups可以有多個值但是靜態值，parallel_instance_group可以在系統級別與會話級別進行修改。
在Oracle 10g RAC中，為了使用並行執行需要設定parallel_instance_group引數，並且parallel_instance_group的值必須是該例項instance_groups所指定的引數值之一。
例如，有一個3節點的Oracle 10g RAC在spfile中有以下設定:
myrac1.instance_groups='rac','rac1'
myrac2.instance_groups='rac','rac2'
myrac3.instance_groups='rac','rac3'
myrac1.parallel_instance_group='rac1'#節點1的並行執行只能在節點1上執行
myrac2.parallel_instance_group='rac2'#節點2的並行執行只能在節點2上執行
myrac3.parallel_instance_group='rac3'#節點3的並行執行只能在節點3上執行
在11gRAC中，因為向後相容仍然可以使用instance_groups和parallel_instance_group引數。然而，在Oracle 11g RAC中不需要這樣做，instance_groups引數已經被廢棄並且保留只是為了向後相容。
在Oracle 11gRAC中並行查詢子程式與服務整合在一起，因此不需要再設定instance_groups和parallel_instance_group引數。因為不需要設定instance_groups引數，而是可以直接設定服務名，
例如:alter session set parallel_instance_group=service_name。因為在11g中instance_groups引數已經被廢棄，可以繼續使用，但是它只是為了向後相容。
在Oracle 11g RAC中也可以不需要設定parallel_instance_groups引數來限制並行查詢子程式在指定的例項上執行。如果以並行方式來執行SQL語句，那麼預設情況下並行程式只會在你透過服務名所連線到的資料庫例項上執行。這不會影響其它的並行操作比如並行恢復或gv$檢視的查詢處理。為了覆蓋這種行為，可以設定parallel_instance_group引數。
可以使用srvctl add service命令來建立服務。例如，資料庫名是rac且有2個例項，rac1和rac2。
對每個例項建立一個服務
[grid@rac1 ~]$ srvctl add service -d rac -s rac1 -r rac1 -a rac2 [grid@rac1 ~]$ srvctl add service -d rac -s rac2 -r rac2 -a rac1 [grid@rac1 ~]$ srvctl start service -d rac -s rac1 [grid@rac1 ~]$ srvctl start service -d rac -s rac2
上面的語句將建立兩個服務，每個例項一個，-r引數指定首選例項，-a引數指定可用例項。
1.如果使用其中的一個服務連線資料庫，並且沒有顯式地設定parallel_instance_groups引數，那麼並行執行將被限制在你的連線的例項上執行
例如，如果連線到rac1，因上連線到rac1例項，那麼並行查詢了程式將只能在rac1的r引數所指定的例項rac1上執行。
SQL> conn sys/system@rac1 as sysdba
SQL> select instance_name from v$instance;
INSTANCE_NAME
----------------
rac1
SQL> show parameter parallel_instance_group
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
parallel_instance_group string
SQL> show parameter instance_groups
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
instance_groups string
SQL> show parameter parallel_degree_policy
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
parallel_degree_policy string auto
SQL> set timing on
SQL> set autotrace on
SQL> select /*+ parallel(t1,60) */ count(*) from t1;
COUNT(*)
----------
11121536
Elapsed: 00:00:41.25
Execution Plan
----------------------------------------------------------
Plan hash value: 3110199320
--------------------------------------------------------------------------------
------------------------
| Id | Operation | Name | Rows | Cost (%CPU)| Time | T
Q |IN-OUT| PQ Distrib |
--------------------------------------------------------------------------------
------------------------
| 0 | SELECT STATEMENT | | 1 | 793 (0)| 00:00:01 |
| | |
| 1 | SORT AGGREGATE | | 1 | | |
| | |
| 2 | PX COORDINATOR | | | | |
| | |
| 3 | PX SEND QC (RANDOM) | :TQ10000 | 1 | | | Q1,
00 | P->S | QC (RAND) |
| 4 | SORT AGGREGATE | | 1 | | | Q1,
00 | PCWP | |
| 5 | PX BLOCK ITERATOR | | 10M| 793 (0)| 00:00:01 | Q1,
00 | PCWC | |
| 6 | TABLE ACCESS FULL| T1 | 10M| 793 (0)| 00:00:01 | Q1,
00 | PCWP | |
--------------------------------------------------------------------------------
------------------------
Note
-----
- dynamic sampling used for this statement (level=2)
- Degree of Parallelism is 60 because of hint
Statistics
----------------------------------------------------------
430 recursive calls
0 db block gets
281608 consistent gets
158184 physical reads
3328 redo size
425 bytes sent via SQL*Net to client
419 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
21 sorts (memory)
0 sorts (disk)
1 rows processed
在執行時查詢並行子程式的是否只在rac1上執行
SQL> SELECT inst_id,sid, event, seq#,p1,p2,p3, wait_time FROM gv$session_wait WHERE upper(event) like ('PX%') ORDER BY 1;
INST_ID SID EVENT SEQ# P1 P2 P3 WAIT_TIME
---------- ---------- ---------------------------------------------------------------- ---------- ---------- ---------- ---------- ----------
1 29 PX Deq: Execution Msg 54 268566527 1 1113052640 -1
1 105 PX Deq: Execution Msg 2 268566527 1 1113043256 -1
1 43 PX Deq: Execution Msg 57 268566527 1 1113057500 0
1 44 PX Deq: Execution Msg 55 268566527 1 1011415624 -1
1 50 PX Deq: Execution Msg 45 268566527 1 1113065368 -1
1 53 PX Deq: Execution Msg 64 268566527 1 1113070008 0
1 54 PX Deq: Execute Reply 8603 200 1 0 0
1 55 PX Deq: Execution Msg 59 268566527 1 1113049700 -1
1 62 PX Deq: Execution Msg 68 268566527 1 1113067520 0
1 69 PX Deq: Execution Msg 53 268566527 1 1113068028 0
1 74 PX Deq: Execution Msg 60 268566527 1 1113066504 -1
INST_ID SID EVENT SEQ# P1 P2 P3 WAIT_TIME
---------- ---------- ---------------------------------------------------------------- ---------- ---------- ---------- ---------- ----------
1 79 PX Deq: Execute Reply 641 200 1 0 0
1 80 PX Deq: Execution Msg 59 268566527 1 1113068568 -1
1 81 PX Deq: Execution Msg 63 268566527 1 1113069048 -1
1 88 PX Deq: Execution Msg 59 268566527 1 1113051680 0
1 97 PX Deq: Execution Msg 46 268566527 1 1011409340 0
16 rows selected.
可以看到並行子程式全都是在例項rac1上執行。
2.一旦建立這些服務名之後，服務名rac1和rac2可以作為parallel_instance_groups的引數值，不管你使用那個服務名來進行資料庫連線例如，如果使用通用的資料庫服務名rac來進行連線，發現連線到了rac1例項，那麼並行子程式會在當前所連線的例項或所有例項上執行。
SQL> conn sys/system@rac as sysdba
SQL> select instance_name from v$instance;
INSTANCE_NAME
----------------
rac1
SQL> show parameter parallel_instance_group
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
parallel_instance_group string
SQL> show parameter instance_groups
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
instance_groups string
SQL> show parameter parallel_degree_policy
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
parallel_degree_policy string auto
SQL> set timing on
SQL> set autotrace on
SQL> select /*+ parallel(t1,60) */ count(*) from t1;
COUNT(*)
----------
11121536
Elapsed: 00:00:41.25
Execution Plan
----------------------------------------------------------
Plan hash value: 3110199320
--------------------------------------------------------------------------------
------------------------
| Id | Operation | Name | Rows | Cost (%CPU)| Time | T
Q |IN-OUT| PQ Distrib |
--------------------------------------------------------------------------------
------------------------
| 0 | SELECT STATEMENT | | 1 | 793 (0)| 00:00:01 |
| | |
| 1 | SORT AGGREGATE | | 1 | | |
| | |
| 2 | PX COORDINATOR | | | | |
| | |
| 3 | PX SEND QC (RANDOM) | :TQ10000 | 1 | | | Q1,
00 | P->S | QC (RAND) |
| 4 | SORT AGGREGATE | | 1 | | | Q1,
00 | PCWP | |
| 5 | PX BLOCK ITERATOR | | 10M| 793 (0)| 00:00:01 | Q1,
00 | PCWC | |
| 6 | TABLE ACCESS FULL| T1 | 10M| 793 (0)| 00:00:01 | Q1,
00 | PCWP | |
--------------------------------------------------------------------------------
------------------------
Note
-----
- dynamic sampling used for this statement (level=2)
- Degree of Parallelism is 60 because of hint
Statistics
----------------------------------------------------------
430 recursive calls
0 db block gets
281608 consistent gets
158184 physical reads
3328 redo size
425 bytes sent via SQL*Net to client
419 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
21 sorts (memory)
0 sorts (disk)
1 rows processed
在執行時查詢並行子程式的是否只在rac1上執行
SQL> SELECT inst_id,sid, event, seq#,p1,p2,p3, wait_time FROM gv$session_wait WHERE upper(event) like ('PX%') ORDER BY 1;
INST_ID SID EVENT SEQ# P1 P2 P3 WAIT_TIME
---------- ---------- ---------------------------------------------------------------- ---------- ---------- ---------- ---------- ----------
1 29 PX Deq: Execution Msg 43 268566527 1 1113052640 0
1 33 PX Deq: Execute Reply 60924 200 1 0 0
1 104 PX Deq: Execution Msg 51 268566527 1 1113063216 0
1 103 PX Deq: Execution Msg 48 268566527 1 1011409820 0
1 101 PX Deq: Execution Msg 53 268566527 1 1113042688 0
1 100 PX Deq: Execution Msg 53 268566527 1 1011414604 0
1 99 PX Deq: Execution Msg 54 268566527 1 1113050660 0
1 91 PX Deq: Execution Msg 59 268566527 1 1113054620 0
1 90 PX Deq: Execution Msg 47 268566527 1 1011408860 0
1 88 PX Deq: Execution Msg 60 268566527 1 1113043256 0
1 87 PX Deq: Execution Msg 45 268566527 1 1113046760 0
1 86 PX Deq: Execution Msg 52 268566527 1 1113065936 0
1 85 PX Deq: Execution Msg 45 268566527 1 1113062708 0
1 84 PX Deq: Execution Msg 59 268566527 1 1011409340 0
1 83 PX Deq: Execution Msg 45 268566527 1 1113043764 0
1 82 PX Deq: Execution Msg 46 268566527 1 1113059480 0
1 81 PX Deq: Execution Msg 52 268566527 1 1113064800 0
1 80 PX Deq: Execution Msg 43 268566527 1 1113066504 0
1 76 PX Deq: Execution Msg 61 268566527 1 1113056540 0
1 69 PX Deq: Execution Msg 48 268566527 1 1113067012 0
1 68 PX Deq: Execution Msg 48 268566527 1 1113049700 0
1 66 PX Deq: Execution Msg 61 268566527 1 1011415624 0
1 64 PX Deq: Execution Msg 2 268566527 1 1113068028 -1
1 62 PX Deq: Execution Msg 39 268566527 1 1113067520 0
1 59 PX Deq: Execution Msg 49 268566527 1 1113044840 0
1 58 PX Deq: Execution Msg 47 268566527 1 1113048740 0
1 57 PX Deq: Execution Msg 50 268566527 1 1113064232 0
1 54 PX Deq: Execute Reply 11610 200 1 0 0
1 53 PX Deq: Execution Msg 52 268566527 1 1113065368 0
1 43 PX Deq: Execution Msg 42 268566527 1 1113047780 0
2 80 PX Deq: Execution Msg 133 268566527 2 1112541100 0
2 83 PX Deq: Execution Msg 119 268566527 2 1112529160 0
2 78 PX Deq: Execution Msg 107 268566527 2 1112534620 0
2 77 PX Deq: Execution Msg 144 268566527 2 1112535100 0
2 76 PX Deq: Execution Msg 146 268566527 2 1112540140 0
2 74 PX Deq: Execution Msg 118 268566527 2 1112530660 0
2 73 PX Deq: Execution Msg 150 268566527 2 1112536660 0
2 72 PX Deq: Execution Msg 125 268566527 2 1112531140 0
2 71 PX Deq: Execution Msg 157 268566527 2 1112533660 0
2 70 PX Deq: Execution Msg 146 268566527 2 1112530180 0
2 69 PX Deq: Execution Msg 135 268566527 2 1112532640 0
2 67 PX Deq: Execution Msg 128 268566527 2 1112556120 0
2 66 PX Deq: Execution Msg 135 268566527 2 1112532100 0
2 65 PX Deq: Execution Msg 124 268566527 2 1112555640 0
2 63 PX Deq: Execution Msg 126 268566527 2 1112528620 0
2 62 PX Deq: Execution Msg 183 268566527 2 1112537140 0
2 60 PX Deq: Execution Msg 182 268566527 2 1112541580 0
2 59 PX Deq: Execution Msg 103 268566527 2 1112535580 0
2 58 PX Deq: Execution Msg 160 268566527 2 1112539600 0
2 57 PX Deq: Execution Msg 164 268566527 2 1112538580 0
2 56 PX Deq: Execution Msg 124 268566527 2 1112527528 0
2 53 PX Deq: Execution Msg 145 268566527 2 1112539060 0
2 49 PX Deq: Execution Msg 140 268566527 2 1112538100 0
2 37 PX Deq: Execution Msg 112 268566527 2 1112537620 0
2 36 PX Deq: Execution Msg 153 268566527 1 1112536120 0
2 34 PX Deq: Execution Msg 14 268566527 2 1112531620 -1
2 81 PX Deq: Execution Msg 157 268566527 2 1112533180 0
2 79 PX Deq: Execution Msg 128 268566527 2 1112557244 0
58 rows selected.
從上面的資訊可以看到透過通用服務名rac雖然連線到的例項是rac1,在執行並行查詢時並行子程式在例項rac1與rac2上執行，並不是只在rac1例項上執行。
如果你想限制你的查詢只在rac1例項上執行，那麼執行
alter session set parallel_instance_group=rac1命令，這將限制並行子程式只在指定服務名所相關的例項上執行，比如rac1。
SQL> alter session set parallel_instance_group='rac1';
Session altered.
SQL> show parameter parallel_instance_group
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
parallel_instance_group string rac1
SQL> select /*+ parallel(t1,60) */ count(*) from t1;
COUNT(*)
----------
11121536
Elapsed: 00:00:41.25
Execution Plan
----------------------------------------------------------
Plan hash value: 3110199320
--------------------------------------------------------------------------------
------------------------
| Id | Operation | Name | Rows | Cost (%CPU)| Time | T
Q |IN-OUT| PQ Distrib |
--------------------------------------------------------------------------------
------------------------
| 0 | SELECT STATEMENT | | 1 | 793 (0)| 00:00:01 |
| | |
| 1 | SORT AGGREGATE | | 1 | | |
| | |
| 2 | PX COORDINATOR | | | | |
| | |
| 3 | PX SEND QC (RANDOM) | :TQ10000 | 1 | | | Q1,
00 | P->S | QC (RAND) |
| 4 | SORT AGGREGATE | | 1 | | | Q1,
00 | PCWP | |
| 5 | PX BLOCK ITERATOR | | 10M| 793 (0)| 00:00:01 | Q1,
00 | PCWC | |
| 6 | TABLE ACCESS FULL| T1 | 10M| 793 (0)| 00:00:01 | Q1,
00 | PCWP | |
--------------------------------------------------------------------------------
------------------------
Note
-----
- dynamic sampling used for this statement (level=2)
- Degree of Parallelism is 60 because of hint
Statistics
----------------------------------------------------------
430 recursive calls
0 db block gets
281608 consistent gets
158184 physical reads
3328 redo size
425 bytes sent via SQL*Net to client
419 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
21 sorts (memory)
0 sorts (disk)
1 rows processed
SQL> SELECT inst_id,sid, event, seq#,p1,p2,p3, wait_time FROM gv$session_wait WHERE upper(event) like ('PX%') ORDER BY 1;
INST_ID SID EVENT SEQ# P1 P2 P3 WAIT_TIME
---------- ---------- ---------------------------------------------------------------- ---------- ---------- ---------- ---------- ----------
1 43 PX Deq: Execution Msg 61 268566527 2 1113060496 0
1 53 PX Deq: Execution Msg 71 268566527 2 1011415624 0
1 54 PX Deq: Parse Reply 28202 200 1 0 -1
1 55 PX Deq: Execution Msg 64 268566527 1 1011418240 0
1 57 PX Deq: Execution Msg 88 268566527 1 1113048740 0
1 58 PX Deq: Execution Msg 53 268566527 1 1113061632 0
1 62 PX Deq: Execution Msg 66 268566527 3 1011420904 0
1 64 PX Deq: Execution Msg 58 268566527 1 1011407468 0
1 66 PX Deq: Execution Msg 75 268566527 2 1113061124 0
1 67 PX Deq: Execution Msg 2 268566527 1 1113079488 -1
1 68 PX Deq: Execution Msg 76 268566527 2 1011417732 0
1 69 PX Deq: Execution Msg 56 268566527 3 1011420424 0
1 76 PX Deq: Execution Msg 70 268566527 1 1011408860 0
1 79 PX Deq: Execute Reply 672 200 1 0 0
1 80 PX Deq: Execution Msg 75 268566527 1 1011419944 0
1 81 PX Deq: Execution Msg 75 268566527 1 1011409340 0
1 82 PX Deq: Execution Msg 63 268566527 1 1113054620 0
1 83 PX Deq: Execution Msg 62 268566527 2 1011407948 0
1 85 PX Deq: Execution Msg 65 268566527 3 1113049700 0
1 86 PX Deq: Execution Msg 54 268566527 2 1113047780 0
1 88 PX Deq: Execution Msg 65 268566527 3 1113059480 0
1 90 PX Deq: Execution Msg 83 268566527 2 1113049220 0
1 91 PX Deq: Execution Msg 65 268566527 1 1113052640 0
1 101 PX Deq: Execution Msg 69 268566527 2 1113053600 0
1 102 PX Deq: Execution Msg 56 268566527 2 1113056540 0
1 103 PX Deq: Execution Msg 70 268566527 2 1113044840 0
1 104 PX Deq: Execution Msg 70 268566527 2 1113046760 0
28 rows selected.
可以看到在設定parallel_instance_group='rac1'後，並行子程式只能在例項rac1上執行了。
3.如果連線的服務名執行在兩個例項上，比如:srvctl add service -d rac -s rac -r rac1,rac2那麼，並行查詢的並行子程式將會執行在兩個例項上，不管你所連線的是那個例項。
SQL> conn sys/system@rac as sysdba
SQL> select instance_name from v$instance;
INSTANCE_NAME
----------------
rac2
SQL> show parameter parallel_instance_group
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
parallel_instance_group string
SQL> show parameter instance_groups
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
instance_groups string
SQL> show parameter parallel_degree_policy
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
parallel_degree_policy string auto
SQL> set timing on
SQL> set autotrace on
SQL> select /*+ parallel(t1,60) */ count(*) from t1;
COUNT(*)
----------
11121536
Elapsed: 00:00:41.25
Execution Plan
----------------------------------------------------------
Plan hash value: 3110199320
--------------------------------------------------------------------------------
------------------------
| Id | Operation | Name | Rows | Cost (%CPU)| Time | T
Q |IN-OUT| PQ Distrib |
--------------------------------------------------------------------------------
------------------------
| 0 | SELECT STATEMENT | | 1 | 793 (0)| 00:00:01 |
| | |
| 1 | SORT AGGREGATE | | 1 | | |
| | |
| 2 | PX COORDINATOR | | | | |
| | |
| 3 | PX SEND QC (RANDOM) | :TQ10000 | 1 | | | Q1,
00 | P->S | QC (RAND) |
| 4 | SORT AGGREGATE | | 1 | | | Q1,
00 | PCWP | |
| 5 | PX BLOCK ITERATOR | | 10M| 793 (0)| 00:00:01 | Q1,
00 | PCWC | |
| 6 | TABLE ACCESS FULL| T1 | 10M| 793 (0)| 00:00:01 | Q1,
00 | PCWP | |
--------------------------------------------------------------------------------
------------------------
Note
-----
- dynamic sampling used for this statement (level=2)
- Degree of Parallelism is 60 because of hint
Statistics
----------------------------------------------------------
430 recursive calls
0 db block gets
281608 consistent gets
158184 physical reads
3328 redo size
425 bytes sent via SQL*Net to client
419 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
21 sorts (memory)
0 sorts (disk)
1 rows processed
SQL> SELECT inst_id,sid, event, seq#,p1,p2,p3, wait_time FROM gv$session_wait WHERE upper(event) like ('PX%') ORDER BY 1;
INST_ID SID EVENT SEQ# P1 P2 P3 WAIT_TIME
---------- ---------- ---------------------------------------------------------------- ---------- ---------- ---------- ---------- ----------
1 29 PX Deq: Execution Msg 43 268566527 1 1113052640 0
1 33 PX Deq: Execute Reply 60924 200 1 0 0
1 104 PX Deq: Execution Msg 51 268566527 1 1113063216 0
1 103 PX Deq: Execution Msg 48 268566527 1 1011409820 0
1 101 PX Deq: Execution Msg 53 268566527 1 1113042688 0
1 100 PX Deq: Execution Msg 53 268566527 1 1011414604 0
1 99 PX Deq: Execution Msg 54 268566527 1 1113050660 0
1 91 PX Deq: Execution Msg 59 268566527 1 1113054620 0
1 90 PX Deq: Execution Msg 47 268566527 1 1011408860 0
1 88 PX Deq: Execution Msg 60 268566527 1 1113043256 0
1 87 PX Deq: Execution Msg 45 268566527 1 1113046760 0
1 86 PX Deq: Execution Msg 52 268566527 1 1113065936 0
1 85 PX Deq: Execution Msg 45 268566527 1 1113062708 0
1 84 PX Deq: Execution Msg 59 268566527 1 1011409340 0
1 83 PX Deq: Execution Msg 45 268566527 1 1113043764 0
1 82 PX Deq: Execution Msg 46 268566527 1 1113059480 0
1 81 PX Deq: Execution Msg 52 268566527 1 1113064800 0
1 80 PX Deq: Execution Msg 43 268566527 1 1113066504 0
1 76 PX Deq: Execution Msg 61 268566527 1 1113056540 0
1 69 PX Deq: Execution Msg 48 268566527 1 1113067012 0
1 68 PX Deq: Execution Msg 48 268566527 1 1113049700 0
1 66 PX Deq: Execution Msg 61 268566527 1 1011415624 0
1 64 PX Deq: Execution Msg 2 268566527 1 1113068028 -1
1 62 PX Deq: Execution Msg 39 268566527 1 1113067520 0
1 59 PX Deq: Execution Msg 49 268566527 1 1113044840 0
1 58 PX Deq: Execution Msg 47 268566527 1 1113048740 0
1 57 PX Deq: Execution Msg 50 268566527 1 1113064232 0
1 54 PX Deq: Execute Reply 11610 200 1 0 0
1 53 PX Deq: Execution Msg 52 268566527 1 1113065368 0
1 43 PX Deq: Execution Msg 42 268566527 1 1113047780 0
2 80 PX Deq: Execution Msg 133 268566527 2 1112541100 0
2 83 PX Deq: Execution Msg 119 268566527 2 1112529160 0
2 78 PX Deq: Execution Msg 107 268566527 2 1112534620 0
2 77 PX Deq: Execution Msg 144 268566527 2 1112535100 0
2 76 PX Deq: Execution Msg 146 268566527 2 1112540140 0
2 74 PX Deq: Execution Msg 118 268566527 2 1112530660 0
2 73 PX Deq: Execution Msg 150 268566527 2 1112536660 0
2 72 PX Deq: Execution Msg 125 268566527 2 1112531140 0
2 71 PX Deq: Execution Msg 157 268566527 2 1112533660 0
2 70 PX Deq: Execution Msg 146 268566527 2 1112530180 0
2 69 PX Deq: Execution Msg 135 268566527 2 1112532640 0
2 67 PX Deq: Execution Msg 128 268566527 2 1112556120 0
2 66 PX Deq: Execution Msg 135 268566527 2 1112532100 0
2 65 PX Deq: Execution Msg 124 268566527 2 1112555640 0
2 63 PX Deq: Execution Msg 126 268566527 2 1112528620 0
2 62 PX Deq: Execution Msg 183 268566527 2 1112537140 0
2 60 PX Deq: Execution Msg 182 268566527 2 1112541580 0
2 59 PX Deq: Execution Msg 103 268566527 2 1112535580 0
2 58 PX Deq: Execution Msg 160 268566527 2 1112539600 0
2 57 PX Deq: Execution Msg 164 268566527 2 1112538580 0
2 56 PX Deq: Execution Msg 124 268566527 2 1112527528 0
2 53 PX Deq: Execution Msg 145 268566527 2 1112539060 0
2 49 PX Deq: Execution Msg 140 268566527 2 1112538100 0
2 37 PX Deq: Execution Msg 112 268566527 2 1112537620 0
2 36 PX Deq: Execution Msg 153 268566527 1 1112536120 0
2 34 PX Deq: Execution Msg 14 268566527 2 1112531620 -1
2 81 PX Deq: Execution Msg 157 268566527 2 1112533180 0
2 79 PX Deq: Execution Msg 128 268566527 2 1112557244 0
58 rows selected.
從上面的資訊可以看到透過通用服務名rac雖然連線到的例項是rac2,在執行並行查詢時並行子程式在例項rac1與rac2上執行，並不是只在rac2例項上執行。
4.如果所連線的例項已經設定了instance_groups，那麼也可以設定parallel_instance_group來進行限制，就像oracle 10g rac一樣。
例項rac1:
SQL> alter system set instance_groups='rac','rac1' scope=spfile sid='rac1'; System altered. SQL> shutdown immediate Database closed. Database dismounted. ORACLE instance shut down. SQL> startup ORA-32004: obsolete or deprecated parameter(s) specified for RDBMS instance ORACLE instance started. Total System Global Area 669581312 bytes Fixed Size 1366724 bytes Variable Size 306185532 bytes Database Buffers 356515840 bytes Redo Buffers 5513216 bytes Database mounted. Database opened. SQL> show parameter instance_groups NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ instance_groups string rac, rac1 SQL> show parameter parallel_instance_group NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ parallel_instance_group string
將parallel_instance_group設定為rac，並行子程式可能會在例項rac1與rac2上執行
SQL> alter session set parallel_instance_group='rac';
Session altered.
SQL> show parameter parallel_instance_group
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
parallel_instance_group string rac
SQL> set autotrace on
SQL> select /*+ parallel(t1,60) */ count(*) from t1;
COUNT(*)
----------
11121536
Execution Plan
----------------------------------------------------------
Plan hash value: 3110199320
--------------------------------------------------------------------------------
------------------------
| Id | Operation | Name | Rows | Cost (%CPU)| Time | T
Q |IN-OUT| PQ Distrib |
--------------------------------------------------------------------------------
------------------------
| 0 | SELECT STATEMENT | | 1 | 793 (0)| 00:00:01 |
| | |
| 1 | SORT AGGREGATE | | 1 | | |
| | |
| 2 | PX COORDINATOR | | | | |
| | |
| 3 | PX SEND QC (RANDOM) | :TQ10000 | 1 | | | Q1,
00 | P->S | QC (RAND) |
| 4 | SORT AGGREGATE | | 1 | | | Q1,
00 | PCWP | |
| 5 | PX BLOCK ITERATOR | | 10M| 793 (0)| 00:00:01 | Q1,
00 | PCWC | |
| 6 | TABLE ACCESS FULL| T1 | 10M| 793 (0)| 00:00:01 | Q1,
00 | PCWP | |
--------------------------------------------------------------------------------
------------------------
Note
-----
- dynamic sampling used for this statement (level=5)
- Degree of Parallelism is 60 because of hint
Statistics
----------------------------------------------------------
250 recursive calls
4 db block gets
162870 consistent gets
158172 physical reads
0 redo size
425 bytes sent via SQL*Net to client
419 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
SQL> SELECT inst_id,sid, event, seq#,p1,p2,p3, wait_time FROM gv$session_wait WHERE upper(event) like ('PX%') ORDER BY 1;
INST_ID SID EVENT SEQ# P1 P2 P3 WAIT_TIME
---------- ---------- ---------------------------------------------------------------- ---------- ---------- ---------- ---------- ----------
1 1 PX Deq: Execute Reply 11283 200 1 0 0
1 35 PX Deq: Execution Msg 45 268566527 1 1113085912 0
1 86 PX Deq: Execution Msg 36 268566527 1 1039760268 0
1 85 PX Deq: Execution Msg 42 268566527 1 1039763628 0
1 84 PX Deq: Execution Msg 40 268566527 1 1039764108 0
1 83 PX Deq: Execution Msg 49 268566527 2 1039764588 0
1 81 PX Deq: Execution Msg 42 268566527 1 1113034840 0
1 80 PX Deq: Execution Msg 33 268566527 1 1113035320 0
1 78 PX Deq: Execution Msg 37 268566527 1 1113036280 0
1 77 PX Deq: Execution Msg 54 268566527 1 1113058080 0
1 75 PX Deq: Execution Msg 2 268566527 1 1039758828 -1
1 74 PX Deq: Execution Msg 50 268566527 2 1113088316 0
1 73 PX Deq: Execution Msg 54 268566527 1 1113037780 0
1 72 PX Deq: Execution Msg 50 268566527 1 1113062540 0
1 70 PX Deq: Execution Msg 46 268566527 1 1113063500 0
1 69 PX Deq: Execution Msg 54 268566527 1 1113038740 0
1 68 PX Deq: Execution Msg 60 268566527 1 1113060560 0
1 66 PX Deq: Execution Msg 43 268566527 2 1113061520 0
1 65 PX Deq: Execution Msg 56 268566527 1 1113039760 0
1 63 PX Deq: Execution Msg 64 268566527 1 1113040780 0
1 62 PX Deq: Execution Msg 59 268566527 1 1113040240 0
1 61 PX Deq: Execution Msg 69 268566527 1 1113059600 0
1 60 PX Deq: Execution Msg 70 268566527 2 1113057120 0
1 58 PX Deq: Execution Msg 46 268566527 2 1113041260 0
1 50 PX Deq: Execute Reply 5402 200 1 0 0
1 36 PX Deq: Execution Msg 41 268566527 1 1113037300 0
2 29 PX Deq: Execution Msg 175 268566527 2 1113084304 0
2 79 PX Deq: Execution Msg 99 268566527 2 1113067788 0
2 77 PX Deq: Execution Msg 123 268566527 2 1113068868 0
2 76 PX Deq: Execution Msg 119 268566527 2 1113069348 0
2 72 PX Deq: Execution Msg 146 268566527 2 1113071268 0
2 71 PX Deq: Execution Msg 131 268566527 2 1113071868 0
2 70 PX Deq: Execution Msg 105 268566527 2 1113072348 0
2 69 PX Deq: Execution Msg 147 268566527 2 1113072828 0
2 68 PX Deq: Execution Msg 109 268566527 2 1113073308 0
2 63 PX Deq: Execution Msg 155 268566527 2 1113087304 0
2 62 PX Deq: Execution Msg 129 268566527 2 1113074268 0
2 61 PX Deq: Execution Msg 113 268566527 2 1113096428 0
2 59 PX Deq: Execution Msg 149 268566527 2 1113087784 0
2 58 PX Deq: Execution Msg 134 268566527 2 1113085264 0
2 57 PX Deq: Execution Msg 155 268566527 2 1113084784 0
2 56 PX Deq: Execution Msg 156 268566527 2 1113082384 0
2 54 PX Deq: Execution Msg 167 268566527 2 1113081784 0
2 53 PX Deq: Execution Msg 147 268566527 2 1113085864 0
2 49 PX Deq: Execution Msg 144 268566527 2 1113083344 0
2 48 PX Deq: Execution Msg 167 268566527 2 1113095304 0
2 47 PX Deq: Execution Msg 128 268566527 2 1113083824 0
2 44 PX Deq: Execution Msg 14 268566527 2 1113067308 -1
2 37 PX Deq: Execution Msg 151 268566527 2 1113086344 0
2 36 PX Deq: Execution Msg 148 268566527 2 1113082864 0
2 35 PX Deq: Execution Msg 133 268566527 2 1113094824 0
2 78 PX Deq: Execution Msg 102 268566527 2 1113068388 0
52 rows selected.
從上面的資訊可以看到當instance_groups設定為'rac','rac1'，且parallel_instance_group設定為'rac'時，在例項rac1上執行並行查詢時並行子程式能在rac1與rac2例項上執行。
將parallel_instance_group設定為rac1時，並行子程式就只能在rac1例項上執行
SQL> alter session set parallel_instance_group='rac1';
Session altered.
SQL> show parameter parallel_instance_group
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
parallel_instance_group string rac1
SQL> select /*+ parallel(t1,60) */ count(*) from t1;
COUNT(*)
----------
11121536
Execution Plan
----------------------------------------------------------
Plan hash value: 3110199320
--------------------------------------------------------------------------------
------------------------
| Id | Operation | Name | Rows | Cost (%CPU)| Time | T
Q |IN-OUT| PQ Distrib |
--------------------------------------------------------------------------------
------------------------
| 0 | SELECT STATEMENT | | 1 | 793 (0)| 00:00:01 |
| | |
| 1 | SORT AGGREGATE | | 1 | | |
| | |
| 2 | PX COORDINATOR | | | | |
| | |
| 3 | PX SEND QC (RANDOM) | :TQ10000 | 1 | | | Q1,
00 | P->S | QC (RAND) |
| 4 | SORT AGGREGATE | | 1 | | | Q1,
00 | PCWP | |
| 5 | PX BLOCK ITERATOR | | 10M| 793 (0)| 00:00:01 | Q1,
00 | PCWC | |
| 6 | TABLE ACCESS FULL| T1 | 10M| 793 (0)| 00:00:01 | Q1,
00 | PCWP | |
--------------------------------------------------------------------------------
------------------------
Note
-----
- dynamic sampling used for this statement (level=5)
- Degree of Parallelism is 60 because of hint
Statistics
----------------------------------------------------------
140 recursive calls
0 db block gets
161150 consistent gets
158026 physical reads
0 redo size
425 bytes sent via SQL*Net to client
419 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
SQL> SELECT inst_id,sid, event, seq#,p1,p2,p3, wait_time FROM gv$session_wait WHERE upper(event) like ('PX%') ORDER BY 1;
INST_ID SID EVENT SEQ# P1 P2 P3 WAIT_TIME
---------- ---------- ---------------------------------------------------------------- ---------- ---------- ---------- ---------- ----------
1 1 PX Deq: Execute Reply 12755 200 1 0 0
1 34 PX Deq: Execution Msg 61 268566527 1 1113057120 0
1 35 PX Deq: Execution Msg 75 268566527 1 1113075080 0
1 36 PX Deq: Execution Msg 56 268566527 1 1113058640 0
1 47 PX Deq: Execution Msg 39 268566527 1 1113071544 0
1 50 PX Deq: Execute Reply 8426 200 1 0 0
1 58 PX Deq: Execution Msg 63 268566527 1 1113036280 0
1 60 PX Deq: Execution Msg 67 268566527 1 1113087836 0
1 61 PX Deq: Execution Msg 70 268566527 1 1113078440 0
1 62 PX Deq: Execution Msg 51 268566527 1 1113085912 0
1 63 PX Deq: Execution Msg 64 268566527 1 1039759788 0
1 64 PX Deq: Execution Msg 87 268566527 1 1113077960 0
1 65 PX Deq: Execution Msg 51 268566527 1 1113088316 0
1 67 PX Deq: Execution Msg 58 268566527 1 1113062540 0
1 68 PX Deq: Execution Msg 67 268566527 1 1113077000 0
1 69 PX Deq: Execution Msg 50 268566527 1 1113063500 0
1 70 PX Deq: Execution Msg 55 268566527 1 1113076520 0
1 72 PX Deq: Execution Msg 63 268566527 1 1113076040 0
1 73 PX Deq: Execution Msg 60 268566527 1 1113061520 0
1 74 PX Deq: Execution Msg 64 268566527 1 1113075560 0
1 75 PX Deq: Execution Msg 75 268566527 1 1113072052 0
1 76 PX Deq: Execution Msg 45 268566527 1 1039764108 0
1 78 PX Deq: Execution Msg 48 268566527 1 1113074060 0
1 79 PX Deq: Execution Msg 53 268566527 1 1113073520 0
1 80 PX Deq: Execution Msg 73 268566527 1 1113058080 0
1 81 PX Deq: Execution Msg 55 268566527 1 1113073040 0
1 82 PX Deq: Execution Msg 64 268566527 1 1039759308 0
1 83 PX Deq: Execution Msg 63 268566527 1 1113072560 0
1 84 PX Deq: Execution Msg 58 268566527 1 1039758348 0
1 86 PX Deq: Execution Msg 55 268566527 1 1113059600 0
1 87 PX Deq: Execution Msg 79 268566527 1 1113074540 0
1 88 PX Deq: Execution Msg 35 268566527 1 1113035320 0
1 89 PX Deq: Execution Msg 38 268566527 1 1113070976 0
1 92 PX Deq: Execution Msg 38 268566527 1 1039753980 0
1 93 PX Deq: Execution Msg 38 268566527 1 1113069840 0
1 94 PX Deq: Execution Msg 54 268566527 1 1039753500 0
1 95 PX Deq: Execution Msg 51 268566527 1 1113069332 0
1 96 PX Deq: Execution Msg 49 268566527 1 1039753020 0
1 98 PX Deq: Execution Msg 2 268566527 1 1113063980 -1
40 rows selected.
從上面的資訊可以看到當instance_groups設定為'rac','rac1'，且parallel_instance_group設定為'rac1'時，在例項rac1上執行並行查詢時並行子程式只能在rac1上執行。
parallel_instance_group
在Oracle 10g中 parallel_instance_group的引數值必須是instance_groups的引數列表之一。在11g中這個列表已經擴充套件包含了所有當前被啟用的服務。因此，parallel_instance_group在11g中它的值可以在instance_groups的引數值中找到資料庫當前已經啟用的服務名之一
parallel_force_local
在11gr2中，parallel_force_local控制著Oracle RAC環境中的並行執行。預設情況下， 並行執行的並行子程式可以在任何RAC節點或所有節點上執行。透過設定parallel_force_lcoal為true，並行子程式將會受限制，因此它們只能在與查詢協調者(QC)所在例項上執行。
SQL> alter session set parallel_force_local=true;
Session altered.
SQL> show parameter parallel_force_local
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
parallel_force_local boolean TRUE
SQL> select /*+ parallel(t1,60) */ count(*) from t1;
COUNT(*)
----------
11121536
Execution Plan
----------------------------------------------------------
Plan hash value: 3110199320
--------------------------------------------------------------------------------
------------------------
| Id | Operation | Name | Rows | Cost (%CPU)| Time | T
Q |IN-OUT| PQ Distrib |
--------------------------------------------------------------------------------
------------------------
| 0 | SELECT STATEMENT | | 1 | 793 (0)| 00:00:01 |
| | |
| 1 | SORT AGGREGATE | | 1 | | |
| | |
| 2 | PX COORDINATOR | | | | |
| | |
| 3 | PX SEND QC (RANDOM) | :TQ10000 | 1 | | | Q1,
00 | P->S | QC (RAND) |
| 4 | SORT AGGREGATE | | 1 | | | Q1,
00 | PCWP | |
| 5 | PX BLOCK ITERATOR | | 10M| 793 (0)| 00:00:01 | Q1,
00 | PCWC | |
| 6 | TABLE ACCESS FULL| T1 | 10M| 793 (0)| 00:00:01 | Q1,
00 | PCWP | |
--------------------------------------------------------------------------------
------------------------
Note
-----
- dynamic sampling used for this statement (level=5)
- Degree of Parallelism is 60 because of hint
Statistics
----------------------------------------------------------
140 recursive calls
0 db block gets
161150 consistent gets
158026 physical reads
0 redo size
425 bytes sent via SQL*Net to client
419 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
SQL> SELECT inst_id,sid, event, seq#,p1,p2,p3, wait_time FROM gv$session_wait WHERE upper(event) like ('PX%') ORDER BY 1;
INST_ID SID EVENT SEQ# P1 P2 P3 WAIT_TIME
---------- ---------- ---------------------------------------------------------------- ---------- ---------- ---------- ---------- ----------
1 1 PX Deq: Execute Reply 12755 200 1 0 0
1 34 PX Deq: Execution Msg 61 268566527 1 1113057120 0
1 35 PX Deq: Execution Msg 75 268566527 1 1113075080 0
1 36 PX Deq: Execution Msg 56 268566527 1 1113058640 0
1 47 PX Deq: Execution Msg 39 268566527 1 1113071544 0
1 50 PX Deq: Execute Reply 8426 200 1 0 0
1 58 PX Deq: Execution Msg 63 268566527 1 1113036280 0
1 60 PX Deq: Execution Msg 67 268566527 1 1113087836 0
1 61 PX Deq: Execution Msg 70 268566527 1 1113078440 0
1 62 PX Deq: Execution Msg 51 268566527 1 1113085912 0
1 63 PX Deq: Execution Msg 64 268566527 1 1039759788 0
1 64 PX Deq: Execution Msg 87 268566527 1 1113077960 0
1 65 PX Deq: Execution Msg 51 268566527 1 1113088316 0
1 67 PX Deq: Execution Msg 58 268566527 1 1113062540 0
1 68 PX Deq: Execution Msg 67 268566527 1 1113077000 0
1 69 PX Deq: Execution Msg 50 268566527 1 1113063500 0
1 70 PX Deq: Execution Msg 55 268566527 1 1113076520 0
1 72 PX Deq: Execution Msg 63 268566527 1 1113076040 0
1 73 PX Deq: Execution Msg 60 268566527 1 1113061520 0
1 74 PX Deq: Execution Msg 64 268566527 1 1113075560 0
1 75 PX Deq: Execution Msg 75 268566527 1 1113072052 0
1 76 PX Deq: Execution Msg 45 268566527 1 1039764108 0
1 78 PX Deq: Execution Msg 48 268566527 1 1113074060 0
1 79 PX Deq: Execution Msg 53 268566527 1 1113073520 0
1 80 PX Deq: Execution Msg 73 268566527 1 1113058080 0
1 81 PX Deq: Execution Msg 55 268566527 1 1113073040 0
1 82 PX Deq: Execution Msg 64 268566527 1 1039759308 0
1 83 PX Deq: Execution Msg 63 268566527 1 1113072560 0
1 84 PX Deq: Execution Msg 58 268566527 1 1039758348 0
1 86 PX Deq: Execution Msg 55 268566527 1 1113059600 0
1 87 PX Deq: Execution Msg 79 268566527 1 1113074540 0
1 88 PX Deq: Execution Msg 35 268566527 1 1113035320 0
1 89 PX Deq: Execution Msg 38 268566527 1 1113070976 0
1 92 PX Deq: Execution Msg 38 268566527 1 1039753980 0
1 93 PX Deq: Execution Msg 38 268566527 1 1113069840 0
1 94 PX Deq: Execution Msg 54 268566527 1 1039753500 0
1 95 PX Deq: Execution Msg 51 268566527 1 1113069332 0
1 96 PX Deq: Execution Msg 49 268566527 1 1039753020 0
1 98 PX Deq: Execution Msg 2 268566527 1 1113063980 -1
使用parallel_force_local要並使用instance_groups與parallel_instance_group引數來進行限制要方便很多。
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