下面是测试在不同版本，在主表与子表上进行DML操作时，在主表与子表分别获取TM锁的情况。主键存在的表称为主表，外键存在的表称为子表。分别测试了9i,10g,11g三个测试的情况。
1 创建对象
所有的对象都创建在HTZ用户下，需要在3个版本的数据库都创建。
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drop user htz cascade; create user htz identified by oracle; grant dba to htz; create table htz.htz as select * from dba_objects where object_id is not null and data_object_id is not null and object_id<100; create table htz.htz1 as select * from dba_objects where object_id is not null and data_object_id is not null and object_id<1000; alter table htz.htz1 add constraint pk_htz1 primary key(object_id) alter table htz add constraint fk_htz1 foreign key(object_id) references htz1(object_id); |
查询对象的object_id，在整个实验过程中会用到
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orcl1123.htz.pw > select object_name,to_char(object_id,'xxxxxxxxxx') from dba_objects where object_name in ('HTZ','HTZ1'); OBJECT_NAME TO_CHAR(OBJ -------------------- ----------- HTZ1 127d0 HTZ 127cf orcl9208.htz.pw > select object_name,to_char(object_id,'xxxxxxxxxx') from dba_objects where object_name in ('HTZ','HTZ1'); OBJECT_NAME TO_CHAR(OBJ -------------------- ----------- HTZ 764f HTZ1 7650 orcl1024.htz.pw > col object_name for a20 orcl1024.htz.pw > select object_name,to_char(object_id,'xxxxxxxxxx') from dba_objects where object_name in ('HTZ','HTZ1'); OBJECT_NAME TO_CHAR(OBJ -------------------- ----------- HTZ1 ca5f HTZ ca5e |
2 测试子表有索引，但是外键不在索引第一列
窗口一：
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create index ind_htz on htz(data_object_id,object_id); |
窗口二：
手动在子表上获取TM3级别的锁，需要在3个数据库中同时执行。
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lock table htz.htz in row exclusive mode nowait; |
查询数据库锁模式
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orcl1123.htz.pw > select sid,type,id1,id2,lmode,request from v$lock where type='TM'; SID TY ID1 ID2 LMODE REQUEST ---------- -- ---------- ---------- ---------- ---------- 31 TM 75727 0 3 0 orcl1024.htz.pw > select sid,type,id1,id2,lmode,request from v$lock where type='TM'; SID TY ID1 ID2 LMODE REQUEST ---------- -- ---------- ---------- ---------- ---------- 145 TM 51806 0 3 0 orcl9208.htz.pw > select sid,type,id1,id2,lmode,request from v$lock where type='TM'; SID TY ID1 ID2 LMODE REQUEST ---------- -- ---------- ---------- ---------- ---------- 10 TM 30287 0 3 0 可以看到都占用了3级别的TM锁 |
窗口一：
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conn / as sysdba oradebug setmypid oradebug event 10704 trace name context forever,level 12; oradebug tracefile_name; delete htz.htz1 where object_id=652; |
三个版本的delete语句都被HANG了。
查看一下TRACE文件中的锁获取情况
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[root@orcl1123 # ]grep "TM" /oracle/app/oracle/diag/rdbms/orcl1123/orcl1123/trace/orcl1123_ora_15543.trc ksqgtl *** TM-000127cf-00000000 mode=4 flags=0x401 timeout=21474836 ***在HTZ上面获取4级别的锁 ksqcmi: TM,127cf,0 mode=4 timeout=21474836 [root@orcl1024 # ]grep 'TM' /oracle/app/oracle/admin/orcl1024/udump/orcl1024_ora_15600.trc ksqgtl *** TM-0000ca5e-00000000 mode=4 flags=0x401 timeout=21474836 ***在HTZ上面获取4级别的锁 ksqcmi: TM,ca5e,0 mode=4 timeout=21474836 [root@orcl9208 # ]grep "TM" orcl9208_ora_15596.trc ksqcmi: TM,764f,0 mode=4 timeout=21474836 ****在HTZ上面获取4级别的锁 |
在三个版本中，在子表上面都去申请TM 4的级
退出窗口二，窗口一中的delete正常执行，再次查看锁获取情况
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[root@orcl1123 # ]grep "TM" /oracle/app/oracle/diag/rdbms/orcl1123/orcl1123/trace/orcl1123_ora_15543.trc ksqgtl *** TM-000127cf-00000000 mode=4 flags=0x401 timeout=21474836 *** ksqcmi: TM,127cf,0 mode=4 timeout=21474836 ksqrcl: TM,127cf,0 ksqcmi: TM,127cf,0 mode=0 timeout=0 ksqgtl *** TM-000127d0-00000000 mode=3 flags=0x401 timeout=21474836 *** ksqgtl *** TM-000127cf-00000000 mode=4 flags=0x401 timeout=21474836 *** ksqrcl: TM,127cf,0 ksqcmi: TM,127cf,0 mode=0 timeout=0
[root@orcl1024 # ]grep 'TM' /oracle/app/oracle/admin/orcl1024/udump/orcl1024_ora_15600.trc ksqgtl *** TM-0000ca5e-00000000 mode=4 flags=0x401 timeout=21474836 *** ksqcmi: TM,ca5e,0 mode=4 timeout=21474836 ksqrcl: TM,ca5e,0 ksqcmi: TM,ca5e,0 mode=0 timeout=0 ksqgtl *** TM-0000ca5f-00000000 mode=3 flags=0x401 timeout=21474836 *** ksqgtl *** TM-0000ca5e-00000000 mode=4 flags=0x401 timeout=21474836 *** ksqrcl: TM,ca5e,0 ksqcmi: TM,ca5e,0 mode=0 timeout=0
[root@orcl9208 # ]grep "TM" orcl9208_ora_15596.trc ksqcmi: TM,764f,0 mode=4 timeout=21474836 ksqcmi: TM,764f,0 mode=0 timeout=0 ksqcmi: TM,764f,0 mode=0 timeout=0 |
可以看到在子表外键列不在索引第一列时：DELETE主表记录获取锁为：子表申请TM 4，成功后释放，在主表申请TM3，再子表申请TM 4，DELETE成功后释放表TM 4锁，在COMMIT后释放主表的TM 3的锁。
3 测试子表外键列有索引，并在第一列
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会话二： create index htz.ind_htz on htz.htz(object_id,data_object_id); 会话一 oradebug setmypid oradebug event 10704 trace name context forever,level 12; oradebug tracefile_name; delete htz.htz1 where object_id=651; 3个数据库都正常的执行
orcl1123.htz.pw > oradebug setmypid Statement processed. orcl1123.htz.pw > oradebug event 10704 trace name context forever,level 12; Statement processed. orcl1123.htz.pw > oradebug tracefile_name; /oracle/app/oracle/diag/rdbms/orcl1123/orcl1123/trace/orcl1123_ora_18403.trc orcl1123.htz.pw > delete htz.htz1 where object_id=651;
1 row deleted.
[root@orcl1123 #]grep "TM" /oracle/app/oracle/diag/rdbms/orcl1123/orcl1123/trace/orcl1123_ora_18403.trc ksqgtl *** TM-000127cf-00000000 mode=3 flags=0x401 timeout=21474836 *** ksqgtl *** TM-000127d0-00000000 mode=3 flags=0x401 timeout=21474836 *** [root@orcl9208 # ]grep "TM" /oracle/app/oracle/admin/orcl9208/udump/orcl9208_ora_18406.trc ksqcmi: TM,764f,0 mode=2 timeout=2147483 [root@orcl1024 # ]grep 'TM' /oracle/app/oracle/admin/orcl1024/udump/orcl1024_ora_18492.trc ksqgtl *** TM-0000ca5e-00000000 mode=2 flags=0x401 timeout=21474836 *** ksqcmi: TM,ca5e,0 mode=2 timeout=21474836 ksqgtl *** TM-0000ca5f-00000000 mode=3 flags=0x401 timeout=21474836 *** 查询锁的情况 orcl1123.htz.pw > select sid,type,id1,id2,lmode,request from v$lock where type='TM'; SID TY ID1 ID2 LMODE REQUEST ---------- -- ---------- ---------- ---------- ---------- 1 TM 75727 0 3 0 1 TM 75728 0 3 0 27 TM 75727 0 3 0 orcl9208.htz.pw > select sid,type,id1,id2,lmode,request from v$lock where type='TM'; SID TY ID1 ID2 LMODE REQUEST ---------- -- ---------- ---------- ---------- ---------- 9 TM 30287 0 2 0 9 TM 30288 0 3 0 10 TM 30287 0 3 0 orcl1024.htz.pw > select sid,type,id1,id2,lmode,request from v$lock where type='TM'; SID TY ID1 ID2 LMODE REQUEST ---------- -- ---------- ---------- ---------- ---------- 145 TM 51806 0 3 0 158 TM 51806 0 2 0 158 TM 51807 0 3 0 |
从上面的测试可以看到：子表外键列有索引的时候，主表的DELETE操作，在子表获取TM 3的锁，10g,9i是TM 2的锁，在主表获取TM 3的锁，在DELETE成功后，并没有立即释放TM锁，需要等commit后，才释放锁。
4 测试子表外键列无索引
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drop index htz.ind_htz; lock table htz.htz in row exclusive mode nowait; 会话1 在个会话同时HANG住 [root@orcl1123 #]grep 'TM' /oracle/app/oracle/diag/rdbms/orcl1123/orcl1123/trace/orcl1123_ora_19364.trc ksqgtl *** TM-000127cf-00000000 mode=4 flags=0x401 timeout=21474836 *** ksqcmi: TM,127cf,0 mode=4 timeout=2147483 [root@orcl1024 # ]grep 'TM' /oracle/app/oracle/admin/orcl1024/udump/orcl1024_ora_19462.trc ksqgtl *** TM-0000ca5e-00000000 mode=4 flags=0x401 timeout=21474836 *** ksqcmi: TM,ca5e,0 mode=4 timeout=21474836
[root@orcl9208 # ]grep 'TM' orcl9208_ora_19370.trc ksqcmi: TM,764f,0 mode=4 timeout=21474836 都获取4级别的锁
退出LOCK TABLE会话 [root@orcl1123 #]grep 'TM' /oracle/app/oracle/diag/rdbms/orcl1123/orcl1123/trace/orcl1123_ora_19364.trc ksqgtl *** TM-000127cf-00000000 mode=4 flags=0x401 timeout=21474836 *** ksqcmi: TM,127cf,0 mode=4 timeout=21474836 ksqrcl: TM,127cf,0 ksqcmi: TM,127cf,0 mode=0 timeout=0 ksqgtl *** TM-000127d0-00000000 mode=3 flags=0x401 timeout=21474836 *** ksqgtl *** TM-000127cf-00000000 mode=4 flags=0x401 timeout=21474836 *** ksqrcl: TM,127cf,0 ksqcmi: TM,127cf,0 mode=0 timeout=0
[root@orcl9208 # ]grep 'TM' orcl9208_ora_19370.trc ksqcmi: TM,764f,0 mode=4 timeout=21474836 ksqcmi: TM,764f,0 mode=0 timeout=0 ksqcmi: TM,764f,0 mode=0 timeout=0
[root@orcl1024 # ]grep 'TM' /oracle/app/oracle/admin/orcl1024/udump/orcl1024_ora_19462.trc ksqgtl *** TM-0000ca5e-00000000 mode=4 flags=0x401 timeout=21474836 *** ksqcmi: TM,ca5e,0 mode=4 timeout=21474836 ksqrcl: TM,ca5e,0 ksqcmi: TM,ca5e,0 mode=0 timeout=0 ksqgtl *** TM-0000ca5f-00000000 mode=3 flags=0x401 timeout=21474836 *** ksqgtl *** TM-0000ca5e-00000000 mode=4 flags=0x401 timeout=21474836 *** ksqrcl: TM,ca5e,0 ksqcmi: TM,ca5e,0 mode=0 timeout=0 |
整个测试结果跟测试1结果一样
5 测试子表的delete操作
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oradebug setmypid oradebug event 10704 trace name context forever,level 12; oradebug tracefile_name; delete htz.htz where object_id=2;
1 row deleted. 跟是否有索引无影响 [root@orcl1123 #]grep 'TM' /oracle/app/oracle/diag/rdbms/orcl1123/orcl1123/trace/orcl1123_ora_20307.trc ksqgtl *** TM-000127cf-00000000 mode=3 flags=0x401 timeout=21474836 *** ksqgtl *** TM-000127d0-00000000 mode=3 flags=0x401 timeout=21474836 ***
[root@orcl9208 # ]grep 'TM' orcl9208_ora_20494.trc ksqcmi: TM,7650,0 mode=0 timeout=0 ksqcmi: TM,764f,0 mode=0 timeout=0
[root@orcl1024 # ]grep 'TM' /oracle/app/oracle/admin/orcl1024/udump/orcl1024_ora_20716.trc ksqgtl *** TM-0000ca5e-00000000 mode=3 flags=0x401 timeout=21474836 *** ksqgtl *** TM-0000ca5f-00000000 mode=2 flags=0x401 timeout=21474836 *** |
可以看到：在子表上成功申请TM3级别的锁后，在主表上升级TM 3(11G)TM2(10g)的锁，DELETE语句执行完后，并没有释放。
6 INSERT语句
下面所有的测试只在11G版本中，没有在其它的版本中测试
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insert主表 orcl1123.htz.pw > select object_name,to_char(object_id,'xxxxxxxxxx') from dba_objects where object_name in ('HTZ','HTZ1');
OBJECT_NAME TO_CHAR(OBJ ------------------------------ ----------- HTZ1 127e0 HTZ 127df
orcl1123.htz.pw > conn / as sysdba Connected. orcl1123.htz.pw > oradebug setmypid Statement processed. orcl1123.htz.pw > oradebug event 10704 trace name context forever,level 12; Statement processed. orcl1123.htz.pw > oradebug tracefile_name; /oracle/app/oracle/diag/rdbms/orcl1123/orcl1123/trace/orcl1123_ora_9770.trc
orcl1123.htz.pw > insert into htz.htz1 (object_id) values(100000); 1 row created. orcl1123.htz.pw > commit; Commit complete. orcl1123.htz.pw > oradebug tracefile_name; /oracle/app/oracle/diag/rdbms/orcl1123/orcl1123/trace/orcl1123_ora_9770.trc orcl1123.htz.pw > !grep 'TM' /oracle/app/oracle/diag/rdbms/orcl1123/orcl1123/trace/orcl1123_ora_9770.trc ksqgtl *** TM-000127df-00000000 mode=3 flags=0x401 timeout=21474836 *** ksqgtl *** TM-000127e0-00000000 mode=3 flags=0x401 timeout=21474836 *** ksqrcl: TM,127e0,0 ksqrcl: TM,127df,0 |
在子表成功申请TM 3级别锁后，在主表再升级TM 3级别的锁。
7 子表INSERT语句
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orcl1123.htz.pw > oradebug setmypid Statement processed. orcl1123.htz.pw > oradebug event 10704 trace name context forever,level 12; Statement processed. orcl1123.htz.pw > oradebug tracefile_name; /oracle/app/oracle/diag/rdbms/orcl1123/orcl1123/trace/orcl1123_ora_9964.trc orcl1123.htz.pw > insert into htz.htz (object_id) values(100000); 1 row created. orcl1123.htz.pw > commit; Commit complete. orcl1123.htz.pw > !grep 'TM' /oracle/app/oracle/diag/rdbms/orcl1123/orcl1123/trace/orcl1123_ora_9964.trc ksqgtl *** TM-000127df-00000000 mode=3 flags=0x401 timeout=21474836 *** ksqgtl *** TM-000127e0-00000000 mode=3 flags=0x401 timeout=21474836 *** ksqrcl: TM,127e0,0 ksqrcl: TM,127df,0 |
在子表成功申请TM 3级别锁后，在主表再升级TM 3级别的锁。
8 UPDATE语句
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更新主表 orcl1123.htz.pw > oradebug setmypid Statement processed. orcl1123.htz.pw > oradebug event 10704 trace name context forever,level 12; Statement processed. orcl1123.htz.pw > oradebug tracefile_name; /oracle/app/oracle/diag/rdbms/orcl1123/orcl1123/trace/orcl1123_ora_10491.trc orcl1123.htz.pw > update htz.htz1 set object_id='23000' where object_id='555'; 1 row updated. orcl1123.htz.pw > commit;
Commit complete.
orcl1123.htz.pw > !grep 'TM' /oracle/app/oracle/diag/rdbms/orcl1123/orcl1123/trace/orcl1123_ora_10491.trc ksqgtl *** TM-000127df-00000000 mode=4 flags=0x401 timeout=21474836 *** ksqrcl: TM,127df,0 ksqcmi: TM,127df,0 mode=0 timeout=0 ksqgtl *** TM-000127e0-00000000 mode=3 flags=0x401 timeout=21474836 *** ksqgtl *** TM-000127df-00000000 mode=4 flags=0x401 timeout=21474836 *** ksqrcl: TM,127df,0 ksqcmi: TM,127df,0 mode=0 timeout=0 ksqrcl: TM,127e0,0 跟DELETE主表一样的锁模式 非主键列 orcl1123.htz.pw > update htz.htz1 set owner='HTZ' where object_id=2; 1 row updated. orcl1123.htz.pw > commit; Commit complete. orcl1123.htz.pw > !grep 'TM' /oracle/app/oracle/diag/rdbms/orcl1123/orcl1123/trace/orcl1123_ora_11669.trc ksqgtl *** TM-000127e0-00000000 mode=3 flags=0x401 timeout=21474836 *** ksqrcl: TM,127e0,0 更新非主键列时，只升级主表上面的锁，子表不影响
子表有索引的情况 orcl1123.htz.pw > create index htz.htz_4 on htz.htz(object_id); Index created. orcl1123.htz.pw > update htz.htz1 set object_id=333333 where object_id=333; 1 row updated. orcl1123.htz.pw > commit; Commit complete. [oracle@www.htz.pw sql]$grep 'TM' /oracle/app/oracle/diag/rdbms/orcl1123/orcl1123/trace/orcl1123_ora_11805.trc ksqgtl *** TM-000127df-00000000 mode=3 flags=0x401 timeout=21474836 *** ksqgtl *** TM-000127e0-00000000 mode=3 flags=0x401 timeout=21474836 *** ksqrcl: TM,127e0,0 ksqrcl: TM,127df,0 跟DELETE主表一样的锁模式
更新子表外键列 orcl1123.htz.pw > update htz.htz set object_id=3 where object_id=2; 1 row updated. orcl1123.htz.pw > commit; Commit complete.
orcl1123.htz.pw > !grep 'TM' /oracle/app/oracle/diag/rdbms/orcl1123/orcl1123/trace/orcl1123_ora_10838.trc ksqgtl *** TM-000127df-00000000 mode=3 flags=0x401 timeout=21474836 *** ksqgtl *** TM-000127e0-00000000 mode=3 flags=0x401 timeout=21474836 *** ksqrcl: TM,127e0,0 ksqcmi: TM,127e0,0 mode=0 timeout=0 ksqrcl: TM,127df,0 ksqcmi: TM,127df,0 mode=0 timeout=0 ksqgtl *** TM-000127df-00000000 mode=3 flags=0x401 timeout=21474836 *** ksqgtl *** TM-000127e0-00000000 mode=3 flags=0x401 timeout=21474836 *** ksqrcl: TM,127e0,0 ksqrcl: TM,127df,0 在更新子表外键列中：先申请子表TM3级别的锁，再升级主表的TM3级别的锁，2个都释放，再升级2个表的TM3级别的锁。 |
1，测试环境
10.2.0.1
网友说delete删除表慢，其它表外键引用了此表的列。
创建测试环境：
TEST2的ID列上创建外键，引用TEST1的ID列
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SQL> create table scott.test1 as select rownum id,dbms_random.string('A',20) name from dual connect by rownum<100000; SQL> c/1/2 1* create table scott.test2 as select rownum id,dbms_random.string('A',20) name from dual connect by rownum<100000; SQL> / SQL> alter table scott.test1 add constraint pk_test1_id primary key (id); SQL> alter table scott.test2 add constraint fk_test2_id foreign key (id) references scott.test1(id);
Owner Constraint Column Reference Reference Index tablename Name Name Type STATUS Object Constraint Name ------------------------- ------- ------------ -------- ----------- ----------- ----------- SCOTT:TEST1 PK_TEST1_ID ID Primary key ENABLED . PK_TEST1_ID SCOTT:TEST2 FK_TEST2_ID ID Foreign Key ENABLED SCOTT.TEST1 PK_TEST1_ID |
下面我们测试一下在表上直接删除数据，会报错
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SQL> delete scott.test1; delete scott.test1 * ERROR at line 1: ORA-02292: integrity constraint (SCOTT.FK_TEST2_ID) violated - child record found 所以这里我们先删除test2表中的内容 SQL> delete scott.test2;
99999 rows deleted.
SQL> commit;
Commit complete. |
开始DELETE测试
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SQL> oradebug setmypid Statement processed. SQL> oradebug event 10704 trace name context forever,level 12; Statement processed. SQL> delete scott.test1;
99999 rows deleted.
[oracle@orcl9i sql]$ grep "TM" /oracle/app/oracle/admin/orcl1021/udump/orcl1021_ora_6658.trc|grep "mode=4"|grep "0000c89d"|wc -l 100000
这里可以看到在TEST2上面获取了10W次TM为4(共享锁，阻塞其它的DML语句)，所以意思着在外键表上面做任何的DML语句都会被HANG住的。 SQL> @16to10.sql Enter value for number16: c89d
NUMBER10 ---------------------------- 51357
SQL> @object_by_id.sql
+------------------------------------------------------------------------+ | display one object type,owner,time,status | +------------------------------------------------------------------------+
Enter Search Object Id (i.e. 1235) : 51357
Object Create Last_Ddl OWNER OBJECT_NAME Type Time Time STATUS -------------------- ---------------------- --------------- -------------------- -------------------- ---------- SCOTT TEST2 TABLE 2014-02-14 09:27:29 2014-02-14 09:30:12 VALID
这里发现在TEST2上面获取了10000次TM为4的锁。
SQL> select object_id from dba_objects where object_name='TEST1';
OBJECT_ID ---------- 51356
SQL> @10to16.sql Enter value for number10: 51356
TO_CHAR('51356','XXXXXXXXXXXXXXXXXXXXXXXXXXXX --------------------------------------------- c89c
[oracle@orcl9i sql]$ grep "0000c89c" /oracle/app/oracle/admin/orcl1021/udump/orcl1021_ora_6658.trc|wc -l 1 ksqgtl *** TM-0000c89c-00000000 mode=3 flags=0x401 timeout=21474836 *** 然而在TEST1上面只获取了一次为TM 3的锁。 |
下面是测试在DELETE删除的时候，后台到底在执行什么操作
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SQL> select count(*) from scott.test1;
COUNT(*) ---------- 99999
SQL> select count(*) from scott.test2;
COUNT(*) ---------- 0
SQL> @sess_current.sql =============================================== USERNAME=SYS SESSION ID=144 SERIAL#=22 AUDSID=4294967295 MODULE#=HTZ PID=20 SPID#=7220 TRACE_FILE_LOCATION=/oracle/app/oracle/admin/orcl1021/udump/orcl1021_ora_7220.trc ===============================================
PL/SQL procedure successfully completed.
SQL> oradebug setmypid Statement processed. SQL> oradebug event 10046 trace name context forever,level 12; Statement processed. SQL> delete scott.test1;
过一会儿后，我们SUSPEND这个进程，用于观察 SQL> delete scott.test1; SQL> oradebug setospid 7220; Oracle pid: 20, Unix process pid: 7220, image: oracle@orcl9i (TNS V1-V3) SQL> oradebug suspend; Statement processed.
SQL> select * from v$locked_object;
XIDUSN XIDSLOT XIDSQN OBJECT_ID SESSION_ID ORACLE_USERNAME OS_USER_NAME PROCESS LOCKED_MODE ---------- ---------- ---------- ---------- ---------- ------------------------------ ------------------------------ ------------ ----------- 4 10 295 51356 144 SYS oracle 7219 3
SQL> select * from v$lock where type='TM';
ADDR KADDR SID TY ID1 ID2 LMODE REQUEST CTIME BLOCK ---------------- ---------------- ---------- -- ---------- ---------- ---------- ---------- ---------- ---------- 0000000180BCFB50 0000000180BCFB78 144 TM 51356 0 3 0 102 0
SQL> delete scott.test1;
99999 rows deleted. 这里使用/oracle/app/oracle/admin/orcl1021/udump/orcl1021_ora_7220.trc文件生成一个HTML文件来分析 d:\wendang\SkyDrive\rs2\win\tvdxtat_40beta9>tvdxtat.cmd -s yes -w yes -i orcl1021_ora_7220.trc -o orcl1021_ora_7220.html 00:00:00 WARNING line 20 not processed 00:00:00 WARNING line 22 not processed
整个等待事件
这里我们看到CPU使用占有89.8%，说明整个SQL一直在运行，不停的消耗CPU 下面查看那个SQL消耗大量的CPU CPU overall 8 statements contributed to this event.
这里我们看到是一个递归SQL消耗了84%的CPU。下面查看递归SQL的消息信息，通过下面的信息可以得到，在有外键引用的表上执行DELETE删除操作的时候，每删除一条SQL都会递归去扫描外键所在的表上面是否存在行，如果不存在，删除继续，如果存在，则报错。
Statement 2 overall
Bind Variables 99999 bind variable sets were used to execute this statement. In the following table, only the first 100 bind variable sets are reported.
Execution Plans
Database Call Statistics with Recursive Statements
Database Call Statistics without Recursive Statements
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通过上面的信息，这里我们知道为什么delete会慢了，解决方案很简单，就是在外键列上面创建一个索引就解决问题。
下面通过创建索引来看看扫描效率的变化
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SQL> oradebug setmypid Statement processed. SQL> create index scott.fk_test2_id on scott.test2(id);
Index created.
SQL> oradebug event 10046 trace name context forever ,level 12; Statement processed. SQL> set timing; SP2-0265: timing must be set ON or OFF SQL> set timing on SQL> oradebug tracefile_name; /oracle/app/oracle/admin/orcl1021/udump/orcl1021_ora_7765.trc SQL> delete scott.test1;
99999 rows deleted.
Elapsed: 00:00:01.51
这里可以看到只发了1S就完成了。
下面再生成HMTL文件看一下。 Resource Usage Profile overall current
这里看到等待事件，已经变成了SQL*NET的等待事件。在HTML中也找到不TEST2上面的任何操作了。
下面再看看锁的情况 SQL> oradebug eventdump session; 10046 trace name CONTEXT level 12, forever SQL> oradebug event 10046 trace name context off; Statement processed. SQL> oradebug event 10704 trace name context forever,level 12; Statement processed.
SQL> !rm /oracle/app/oracle/admin/orcl1021/udump/orcl1021_ora_7765.trc SQL> oradebug close_trace Statement processed. SQL> oradebug flush; Statement processed.
SQL> delete scott.test1;
99999 rows deleted.
Elapsed: 00:00:01.74 SQL> oradebug flush; Statement processed.
在TRACE文件中 ksqgtl *** CU-8165f880-00000001 mode=6 flags=0x10 timeout=300 *** ksqgtl: no transaction ksqgtl: use existing ksusetxn DID ksqgtl: ksqgtl *** CU-8156bcb8-00000001 mode=6 flags=0x10 timeout=300 *** ksqgtl: no transaction ksqgtl: use existing ksusetxn DID ksqgtl: ksqgtl *** TM-0000c89c-00000000 mode=3 flags=0x401 timeout=21474836 *** ksqgtl: ksqgtl *** TM-0000c89d-00000000 mode=2 flags=0x401 timeout=21474836 ***
这里我们可以看到在表上面有一个2级别的锁（共享表锁，不能执行DDL语句), SQL> @table_index.sql +----------------------------------------------------------------------------+ | DISPLAY INDEX INFO ABOUT TABLE:TABLE_NAME | +----------------------------------------------------------------------------+ Enter Search Table Owner (i.e. SCOTT|ALL(DEFAULT)) : scott Enter Search Table Name (i.e. DEPT|DEFAULT(ALL)) : test2 Enter Search Index Name (i.e. DEPT|DEFAULT(ALL)) :
OWNER TABLE_NAME tablespace Dinsinct PAR INDEX_NAME name STATUS INDEX_TYPE UNIQUENES PCT LOG B Keys LEAF_BLOCKS NUM_ROWS TI POST COLUMNNAME --------------------------------------------- -------------------- ---------- ---------- --------- ---- --- -- ----------- ----------- ------------ --- ---- -------------------- TEST2:FK_TEST2_ID USERS VALID NORMAL NONUNIQUE 10 YES NO 1 ID
SQL> select object_id from dba_objects where object_name='FK_TEST2_ID';
OBJECT_ID ---------- 51359
SQL> @10to16.sql Enter value for number10: 51359
TO_CHAR('51359','XXXXXXXXXXXXXXXXXXXXXXXXXXXX --------------------------------------------- c89f 在锁文件中，没有找到任何与c89f相当的锁。 |
来自 “ ITPUB博客 ” ，链接：http://blog.itpub.net/30430420/viewspace-1787705/，如需转载，请注明出处，否则将追究法律责任。
转载于:http://blog.itpub.net/30430420/viewspace-1787705/
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