如何测试Oracle并行执行的并行度状况：
可以通过如下的脚本，来查看要求的并行度，和实际获得的并行度。
脚本来自：
http://askdba.org/weblog/forums/topic/query-to-identify-parallel-slaves/
col username for a12
col module for a10 trunc
col state for a20
col "QC SID" for A6
col SID for a10
col "QC/Slave" for A10
col "ReqDOP" for 999
col "ActDOP" for 999
col "slave set" for A10
col event for a25 trunc
col action for a20 trunc
col p1text for a20 trunc
col secwait for 99999
col state for a10 trunc
col object for a25 trunc
col command for a15 trunc
set pages 300 lines 300
select
s.inst_id,
decode(px.qcinst_id,NULL,s.username,
' - '||lower(substr(s.program,length(s.program)-4,4) ) ) "Username",
decode(px.qcinst_id,NULL, 'QC', '(Slave)') "QC/Slave" ,
to_char( px.server_set) "Slave Set",
to_char(s.sid) "SID",
decode(px.qcinst_id, NULL ,to_char(s.sid) ,px.qcsid) "QC SID",
px.req_degree "Requested DOP",
px.degree "Actual DOP",s.module,s.sql_id,s.event,s.status
from
gv$px_session px,
gv$session s
where
px.sid=s.sid (+) and
px.serial#=s.serial# and
px.inst_id = s.inst_id
order by 2 desc;
在Oracel 11.2.0.4进行实际测试，有效。
实际例子：
$cat q00.sql
col username for a12
col module for a10 trunc
col state for a20
col "QC SID" for A6
col SID for a10
col "QC/Slave" for A10
col "ReqDOP" for 999
col "ActDOP" for 999
col "slave set" for A10
col event for a25 trunc
col action for a20 trunc
col p1text for a20 trunc
col secwait for 99999
col state for a10 trunc
col object for a25 trunc
col command for a15 trunc
set pages 300 lines 300
select
s.inst_id,
decode(px.qcinst_id,NULL,s.username,
' - '||lower(substr(s.program,length(s.program)-4,4) ) ) "Username",
decode(px.qcinst_id,NULL, 'QC', '(Slave)') "QC/Slave" ,
to_char( px.server_set) "Slave Set",
to_char(s.sid) "SID",
decode(px.qcinst_id, NULL ,to_char(s.sid) ,px.qcsid) "QC SID",
px.req_degree "Requested DOP",
px.degree "Actual DOP",s.module,s.sql_id,s.event,s.status
from
gv$px_session px,
gv$session s
where
px.sid=s.sid (+) and
px.serial#=s.serial# and
px.inst_id = s.inst_id
order by 2 desc;
==============================
设置参数:
alter system set PARALLEL_MIN_TIME_THRESHOLD=1 scope=spfile;
alter system set PARALLEL_DEGREE_POLICY=auto scope=spfile;
shu immediate
startup
===================================
通过别的Session，查看状况: <<<<<<<<<<<<<<Requested DOP = 6 、 Actual DOP =6
SQL>@q00.sql
INST_ID Username QC/Slave Slave Set SID QC SID Requested DOP Actual DOP MODULE SQL_ID EVENT STATUS
---------- ------------ ---------- ---------- ---------- ------ ------------- ---------- ---------- -------------------- ------------------------- ------------------------
1 U1 QC 125 125 SQL*Plus 9y3cpa2z9r4zw SQL*Net message from clie INACTIVE
1 - p011 (Slave) 2 19 125 6 6 SQL*Plus 9y3cpa2z9r4zw PX Deq: Execution Msg INACTIVE
1 - p010 (Slave) 2 144 125 6 6 SQL*Plus 9y3cpa2z9r4zw PX Deq: Execution Msg INACTIVE
1 - p009 (Slave) 2 33 125 6 6 SQL*Plus 9y3cpa2z9r4zw PX Deq: Execution Msg INACTIVE
1 - p008 (Slave) 2 142 125 6 6 SQL*Plus 9y3cpa2z9r4zw PX Deq: Execution Msg INACTIVE
1 - p007 (Slave) 2 20 125 6 6 SQL*Plus 9y3cpa2z9r4zw PX Deq: Execution Msg INACTIVE
1 - p006 (Slave) 2 139 125 6 6 SQL*Plus 9y3cpa2z9r4zw PX Deq: Execution Msg INACTIVE
1 - p005 (Slave) 1 18 125 6 6 SQL*Plus 9y3cpa2z9r4zw PX Deq Credit: send blkd ACTIVE
1 - p004 (Slave) 1 29 125 6 6 SQL*Plus 9y3cpa2z9r4zw PX Deq Credit: send blkd ACTIVE
1 - p003 (Slave) 1 143 125 6 6 SQL*Plus 9y3cpa2z9r4zw PX Deq Credit: send blkd ACTIVE
1 - p002 (Slave) 1 141 125 6 6 SQL*Plus 9y3cpa2z9r4zw PX Deq Credit: send blkd ACTIVE
1 - p001 (Slave) 1 21 125 6 6 SQL*Plus 9y3cpa2z9r4zw PX Deq Credit: send blkd ACTIVE
1 - p000 (Slave) 1 140 125 6 6 SQL*Plus 9y3cpa2z9r4zw PX Deq Credit: send blkd ACTIVE
13行が選択されました。
SQL>
===================================
修改session 级别并行度，再次确认：
alter session force parallel query parallel 3;
select * from dba_segments,dba_extents;
===================================
通过别的Session，查看状况: <<<<< Requested DOP =3 Actual DOP =3
SQL>@q00.sql
INST_ID Username QC/Slave Slave Set SID QC SID Requested DOP Actual DOP MODULE SQL_ID EVENT STATUS
---------- ------------ ---------- ---------- ---------- ------ ------------- ---------- ---------- -------------------- ------------------------- ------------------------
1 U1 QC 125 125 SQL*Plus 9y3cpa2z9r4zw SQL*Net message from clie INACTIVE
1 - p005 (Slave) 2 20 125 3 3 SQL*Plus 9y3cpa2z9r4zw PX Deq: Execution Msg INACTIVE
1 - p004 (Slave) 2 21 125 3 3 SQL*Plus 9y3cpa2z9r4zw PX Deq: Execution Msg INACTIVE
1 - p003 (Slave) 2 144 125 3 3 SQL*Plus 9y3cpa2z9r4zw PX Deq: Execution Msg INACTIVE
1 - p002 (Slave) 1 140 125 3 3 SQL*Plus 9y3cpa2z9r4zw PX Deq Credit: send blkd ACTIVE
1 - p001 (Slave) 1 19 125 3 3 SQL*Plus 9y3cpa2z9r4zw PX Deq Credit: send blkd ACTIVE
1 - p000 (Slave) 1 148 125 3 3 SQL*Plus 9y3cpa2z9r4zw PX Deq Credit: send blkd ACTIVE
SQL>
===================================
修改session 级别并行度，再次确认：
alter session force parallel query parallel 8;
select * from dba_segments,dba_extents;
===================================
通过别的Session，查看状况: <<<<< Requested DOP = 8 Actual DOP =8
INST_ID Username QC/Slave Slave Set SID QC SID Requested DOP Actual DOP MODULE SQL_ID EVENT STATUS
---------- ------------ ---------- ---------- ---------- ------ ------------- ---------- ---------- -------------------- ------------------------- ------------------------
1 U1 QC 125 125 SQL*Plus 9y3cpa2z9r4zw SQL*Net message from clie INACTIVE
1 - p015 (Slave) 2 153 125 8 8 SQL*Plus 9y3cpa2z9r4zw PX Deq: Execution Msg INACTIVE
1 - p014 (Slave) 2 23 125 8 8 SQL*Plus 9y3cpa2z9r4zw PX Deq: Execution Msg INACTIVE
1 - p013 (Slave) 2 154 125 8 8 SQL*Plus 9y3cpa2z9r4zw PX Deq: Execution Msg INACTIVE
1 - p012 (Slave) 2 29 125 8 8 SQL*Plus 9y3cpa2z9r4zw PX Deq: Execution Msg INACTIVE
1 - p011 (Slave) 2 18 125 8 8 SQL*Plus 9y3cpa2z9r4zw PX Deq: Execution Msg INACTIVE
1 - p010 (Slave) 2 141 125 8 8 SQL*Plus 9y3cpa2z9r4zw PX Deq: Execution Msg INACTIVE
1 - p009 (Slave) 2 33 125 8 8 SQL*Plus 9y3cpa2z9r4zw PX Deq: Execution Msg INACTIVE
1 - p008 (Slave) 2 142 125 8 8 SQL*Plus 9y3cpa2z9r4zw PX Deq: Execution Msg INACTIVE
1 - p007 (Slave) 1 31 125 8 8 SQL*Plus 9y3cpa2z9r4zw PX Deq Credit: send blkd ACTIVE
1 - p006 (Slave) 1 139 125 8 8 SQL*Plus 9y3cpa2z9r4zw PX Deq Credit: send blkd ACTIVE
1 - p005 (Slave) 1 21 125 8 8 SQL*Plus 9y3cpa2z9r4zw PX Deq Credit: send blkd ACTIVE
1 - p004 (Slave) 1 20 125 8 8 SQL*Plus 9y3cpa2z9r4zw PX Deq Credit: send blkd ACTIVE
1 - p003 (Slave) 1 144 125 8 8 SQL*Plus 9y3cpa2z9r4zw PX Deq Credit: send blkd ACTIVE
1 - p002 (Slave) 1 148 125 8 8 SQL*Plus 9y3cpa2z9r4zw PX Deq Credit: send blkd ACTIVE
1 - p001 (Slave) 1 26 125 8 8 SQL*Plus 9y3cpa2z9r4zw PX Deq Credit: send blkd ACTIVE
1 - p000 (Slave) 1 143 125 8 8 SQL*Plus 9y3cpa2z9r4zw PX Deq Credit: send blkd ACTIVE
SQL>