Managing Undo Data
Data undo managing
2023-09-14 09:01:14 时间
Summary
- Configuration Automaitc Undo Management
- 将undo_management设置为auto
- 设置当前的undo tablespace
- Create an UNDO tablespace
- Properly size an UND tablespace
- Obtain undo segment information
little demo
查看一个事务占用了多少undo block？
SQL> create table t2 as select * from all_objects where 1=0; Table created. SQL> select * from t2; no rows selected SQL> desc t2; Name Null? Type ----------------------------------------- -------- ---------------------------- OWNER NOT NULL VARCHAR2(30) OBJECT_NAME NOT NULL VARCHAR2(30) SUBOBJECT_NAME VARCHAR2(30) OBJECT_ID NOT NULL NUMBER DATA_OBJECT_ID NUMBER OBJECT_TYPE VARCHAR2(19) CREATED NOT NULL DATE LAST_DDL_TIME NOT NULL DATE TIMESTAMP VARCHAR2(19) STATUS VARCHAR2(7) TEMPORARY VARCHAR2(1) GENERATED VARCHAR2(1) SECONDARY VARCHAR2(1) NAMESPACE NOT NULL NUMBER EDITION_NAME VARCHAR2(30) SQL> insert into t2 select * from all_objects; 56374 rows created. SQL>
SQL> show user USER is "SYS" SQL> select addr,used_ublk from v$transaction; ADDR USED_UBLK ---------------- ---------- 00000000776652E0 28 SQL>
如何设计规划undo表空间的大小?
SQL> select end_time,begin_time,undoblks from v$undostat; END_TIME BEGIN_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/16 13:00:27 2013/07/16 12:51:53 104 2013/07/16 12:51:53 2013/07/16 12:41:53 14 2013/07/16 12:41:53 2013/07/16 12:31:53 15 2013/07/16 12:31:53 2013/07/16 12:21:53 14 2013/07/16 12:21:53 2013/07/16 12:11:53 17 2013/07/16 12:11:53 2013/07/16 12:01:53 12 2013/07/16 12:01:53 2013/07/16 11:51:53 160 2013/07/16 11:51:53 2013/07/16 11:41:53 13 2013/07/16 11:41:53 2013/07/16 11:31:53 25 2013/07/16 11:31:53 2013/07/16 11:21:53 12 2013/07/16 11:21:53 2013/07/16 11:11:53 17 END_TIME BEGIN_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/16 11:11:53 2013/07/16 11:01:53 15 2013/07/16 11:01:53 2013/07/16 10:51:53 97 2013/07/16 10:51:53 2013/07/16 10:41:53 17 2013/07/16 10:41:53 2013/07/16 10:31:53 12 2013/07/16 10:31:53 2013/07/16 10:21:53 15 2013/07/16 10:21:53 2013/07/16 10:11:53 18 2013/07/16 10:11:53 2013/07/16 10:01:53 12 2013/07/16 10:01:53 2013/07/16 09:51:53 121 2013/07/16 09:51:53 2013/07/16 09:41:53 16 2013/07/16 09:41:53 2013/07/16 09:31:53 18 2013/07/16 09:31:53 2013/07/16 09:21:53 19 END_TIME BEGIN_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/16 09:21:53 2013/07/16 09:11:53 13 2013/07/16 09:11:53 2013/07/16 09:01:53 18 2013/07/16 09:01:53 2013/07/16 08:51:53 83 2013/07/16 08:51:53 2013/07/16 08:41:53 16 2013/07/16 08:41:53 2013/07/16 08:31:53 14 2013/07/16 08:31:53 2013/07/16 08:21:53 13 2013/07/16 08:21:53 2013/07/16 08:11:53 13 2013/07/16 08:11:53 2013/07/16 08:01:53 11 2013/07/16 08:01:53 2013/07/16 07:51:53 109 2013/07/16 07:51:53 2013/07/16 07:41:53 13 2013/07/16 07:41:53 2013/07/16 07:31:53 14 END_TIME BEGIN_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/16 07:31:53 2013/07/16 07:21:53 21 2013/07/16 07:21:53 2013/07/16 07:11:53 14 2013/07/16 07:11:53 2013/07/16 07:01:53 13 2013/07/16 07:01:53 2013/07/16 06:51:53 91 2013/07/16 06:51:53 2013/07/16 06:41:53 12 2013/07/16 06:41:53 2013/07/16 06:31:53 16 2013/07/16 06:31:53 2013/07/16 06:21:53 15 2013/07/16 06:21:53 2013/07/16 06:11:53 16 2013/07/16 06:11:53 2013/07/16 06:01:53 13 2013/07/16 06:01:53 2013/07/16 05:51:53 101 2013/07/16 05:51:53 2013/07/16 05:41:53 13 END_TIME BEGIN_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/16 05:41:53 2013/07/16 05:31:53 14 2013/07/16 05:31:53 2013/07/16 05:21:53 18 2013/07/16 05:21:53 2013/07/16 05:11:53 12 2013/07/16 05:11:53 2013/07/16 05:01:53 10 2013/07/16 05:01:53 2013/07/16 04:51:53 111 2013/07/16 04:51:53 2013/07/16 04:41:53 15 2013/07/16 04:41:53 2013/07/16 04:31:53 14 2013/07/16 04:31:53 2013/07/16 04:21:53 12 2013/07/16 04:21:53 2013/07/16 04:11:53 19 2013/07/16 04:11:53 2013/07/16 04:01:53 16 2013/07/16 04:01:53 2013/07/16 03:51:53 92 END_TIME BEGIN_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/16 03:51:53 2013/07/16 03:41:53 15 2013/07/16 03:41:53 2013/07/16 03:31:53 14 2013/07/16 03:31:53 2013/07/16 03:21:53 14 2013/07/16 03:21:53 2013/07/16 03:11:53 15 2013/07/16 03:11:53 2013/07/16 03:01:53 15 2013/07/16 03:01:53 2013/07/16 02:51:53 93 2013/07/16 02:51:53 2013/07/16 02:41:53 11 2013/07/16 02:41:53 2013/07/16 02:31:53 17 2013/07/16 02:31:53 2013/07/16 02:21:53 15 2013/07/16 02:21:53 2013/07/16 02:11:53 22 2013/07/16 02:11:53 2013/07/16 02:01:53 12 END_TIME BEGIN_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/16 02:01:53 2013/07/16 01:51:53 107 2013/07/16 01:51:53 2013/07/16 01:41:53 13 2013/07/16 01:41:53 2013/07/16 01:31:53 12 2013/07/16 01:31:53 2013/07/16 01:21:53 15 2013/07/16 01:21:53 2013/07/16 01:11:53 14 2013/07/16 01:11:53 2013/07/16 01:01:53 31 2013/07/16 01:01:53 2013/07/16 00:51:53 252 2013/07/16 00:51:53 2013/07/16 00:41:53 15 2013/07/16 00:41:53 2013/07/16 00:31:53 13 2013/07/16 00:31:53 2013/07/16 00:21:53 13 2013/07/16 00:21:53 2013/07/16 00:11:53 16 END_TIME BEGIN_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/16 00:11:53 2013/07/16 00:01:53 21 2013/07/16 00:01:53 2013/07/15 23:51:53 110 2013/07/15 23:51:53 2013/07/15 23:41:53 14 2013/07/15 23:41:53 2013/07/15 23:31:53 13 2013/07/15 23:31:53 2013/07/15 23:21:53 18 2013/07/15 23:21:53 2013/07/15 23:11:53 18 2013/07/15 23:11:53 2013/07/15 23:01:53 16 2013/07/15 23:01:53 2013/07/15 22:51:53 118 2013/07/15 22:51:53 2013/07/15 22:41:53 14 2013/07/15 22:41:53 2013/07/15 22:31:53 14 2013/07/15 22:31:53 2013/07/15 22:21:53 19 END_TIME BEGIN_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/15 22:21:53 2013/07/15 22:11:53 17 2013/07/15 22:11:53 2013/07/15 22:01:53 28 2013/07/15 22:01:53 2013/07/15 21:51:53 1253 2013/07/15 21:51:53 2013/07/15 21:41:53 17 2013/07/15 21:41:53 2013/07/15 21:31:53 10 2013/07/15 21:31:53 2013/07/15 21:21:53 13 2013/07/15 21:21:53 2013/07/15 21:11:53 16 2013/07/15 21:11:53 2013/07/15 21:01:53 12 2013/07/15 21:01:53 2013/07/15 20:51:53 89 2013/07/15 20:51:53 2013/07/15 20:41:53 14 2013/07/15 20:41:53 2013/07/15 20:31:53 13 END_TIME BEGIN_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/15 20:31:53 2013/07/15 20:21:53 12 2013/07/15 20:21:53 2013/07/15 20:11:53 15 2013/07/15 20:11:53 2013/07/15 20:01:53 14 2013/07/15 20:01:53 2013/07/15 19:51:53 94 2013/07/15 19:51:53 2013/07/15 19:41:53 17 2013/07/15 19:41:53 2013/07/15 19:31:53 13 2013/07/15 19:31:53 2013/07/15 19:21:53 16 2013/07/15 19:21:53 2013/07/15 19:11:53 18 2013/07/15 19:11:53 2013/07/15 19:01:53 14 2013/07/15 19:01:53 2013/07/15 18:51:53 93 2013/07/15 18:51:53 2013/07/15 18:41:53 14 END_TIME BEGIN_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/15 18:41:53 2013/07/15 18:31:53 12 2013/07/15 18:31:53 2013/07/15 18:21:53 19 2013/07/15 18:21:53 2013/07/15 18:11:53 16 2013/07/15 18:11:53 2013/07/15 18:01:53 11 2013/07/15 18:01:53 2013/07/15 17:51:53 95 2013/07/15 17:51:53 2013/07/15 17:41:53 12 2013/07/15 17:41:53 2013/07/15 17:31:53 13 2013/07/15 17:31:53 2013/07/15 17:21:53 14 2013/07/15 17:21:53 2013/07/15 17:11:53 14 2013/07/15 17:11:53 2013/07/15 17:01:53 10 2013/07/15 17:01:53 2013/07/15 16:51:53 118 END_TIME BEGIN_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/15 16:51:53 2013/07/15 16:41:53 11 2013/07/15 16:41:53 2013/07/15 16:31:53 17 2013/07/15 16:31:53 2013/07/15 16:21:53 16 2013/07/15 16:21:53 2013/07/15 16:11:53 19 2013/07/15 16:11:53 2013/07/15 16:01:53 12 2013/07/15 16:01:53 2013/07/15 15:51:53 92 2013/07/15 15:51:53 2013/07/15 15:41:53 16 2013/07/15 15:41:53 2013/07/15 15:31:53 13 2013/07/15 15:31:53 2013/07/15 15:21:53 13 2013/07/15 15:21:53 2013/07/15 15:11:53 15 2013/07/15 15:11:53 2013/07/15 15:01:53 14 END_TIME BEGIN_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/15 15:01:53 2013/07/15 14:51:53 109 2013/07/15 14:51:53 2013/07/15 14:41:53 14 2013/07/15 14:41:53 2013/07/15 14:31:53 14 2013/07/15 14:31:53 2013/07/15 14:21:53 12 2013/07/15 14:21:53 2013/07/15 14:11:53 15 2013/07/15 14:11:53 2013/07/15 14:01:53 12 2013/07/15 14:01:53 2013/07/15 13:51:53 94 2013/07/15 13:51:53 2013/07/15 13:41:53 18 2013/07/15 13:41:53 2013/07/15 13:31:53 12 2013/07/15 13:31:53 2013/07/15 13:21:53 17 2013/07/15 13:21:53 2013/07/15 13:11:53 14 END_TIME BEGIN_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/15 13:11:53 2013/07/15 13:01:53 12 2013/07/15 13:01:53 2013/07/15 12:51:53 101 2013/07/15 12:51:53 2013/07/15 12:41:53 16 2013/07/15 12:41:53 2013/07/15 12:31:53 12 2013/07/15 12:31:53 2013/07/15 12:21:53 15 2013/07/15 12:21:53 2013/07/15 12:11:53 16 2013/07/15 12:11:53 2013/07/15 12:01:53 87 2013/07/15 12:01:53 2013/07/15 11:51:53 22 151 rows selected. SQL>
查询undo tablespace
查看数据库有哪些表空间?
SQL> select tablespace_name,status,contents from dba_tablespaces; TABLESPACE_NAME STATUS CONTENTS ------------------------------ --------- --------- SYSTEM ONLINE PERMANENT SYSAUX ONLINE PERMANENT UNDOTBS1 ONLINE UNDO TEMP ONLINE TEMPORARY USERS ONLINE PERMANENT EXAMPLE ONLINE PERMANENT APP_FGPS ONLINE PERMANENT RMAN_TS ONLINE PERMANENT MYUNDOTBS ONLINE UNDO TESTUNDOTBS ONLINE UNDO 10 rows selected.
查看数据库有哪些表空间文件?
SQL> select name,status from v$datafile; NAME STATUS ------------------------------------------------------------ ------- /u01/app/oracle/oradata/testdb/system01.dbf SYSTEM /u01/app/oracle/oradata/testdb/sysaux01.dbf ONLINE /u01/app/oracle/oradata/testdb/undotbs01.dbf ONLINE /u01/app/oracle/oradata/testdb/users01.dbf ONLINE /u01/app/oracle/oradata/testdb/example01.dbf ONLINE /u01/app/oracle/oradata/testdb/DATACENTER01.dbf ONLINE /u01/app/oracle/oradata/testdb/rman_ts01.dbf ONLINE /u01/app/oracle/oradata/testdb/myundotbs01.dbf ONLINE /u01/app/oracle/oradata/testdb/testundotbs01.dbf ONLINE 9 rows selected.
查看当前系统正在使用哪个undo tablespace？
SQL> show parameter undo; NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ undo_management string AUTO undo_retention integer 900 undo_tablespace string MYUNDOTBS
查询指定undo tablespace有哪些undo segments？
SQL> select segment_name,tablespace_name from dba_rollback_segs where tablespace_name='UNDOTBS1'; SEGMENT_NAME TABLESPACE_NAME ------------------------------ ------------------------------ _SYSSMU1_1240252155$ UNDOTBS1 _SYSSMU2_111974964$ UNDOTBS1 _SYSSMU3_4004931649$ UNDOTBS1 _SYSSMU4_1126976075$ UNDOTBS1 _SYSSMU5_4011504098$ UNDOTBS1 _SYSSMU6_3654194381$ UNDOTBS1 _SYSSMU7_4222772309$ UNDOTBS1 _SYSSMU8_3612859353$ UNDOTBS1 _SYSSMU9_3945653786$ UNDOTBS1 _SYSSMU10_3271578125$ UNDOTBS1 10 rows selected.
创建undo tablespace
SQL> create undo tablespace testundotbs datafile '/u01/app/oracle/oradata/testdb/testundotbs01.dbf' size 2M; Tablespace created. SQL>
SQL> create undo tablespace testundotbs datafile '/u01/app/oracle/oradata/testdb/testundotbs01.dbf' size 2M autoextend off; Tablespace created. SQL>
删除undo tablespace
SQL> drop tablespace testundotbs; Tablespace dropped.
11203ora-> ll total 2618412 -rw-r----- 1 oracle oinstall 9814016 Jul 16 16:27 control01.ctl -rw-r----- 1 oracle oinstall 209723392 Jul 16 16:05 DATACENTER01.dbf -rw-r----- 1 oracle oinstall 362422272 Jul 16 16:05 example01.dbf -rw-r----- 1 oracle oinstall 120594432 Jul 16 16:26 myundotbs01.dbf -rw-r----- 1 oracle oinstall 52429312 Jul 15 22:00 redo01.log -rw-r----- 1 oracle oinstall 52429312 Jul 16 16:00 redo02.log -rw-r----- 1 oracle oinstall 52429312 Jul 16 16:26 redo03.log -rw-r----- 1 oracle oinstall 209723392 Jul 16 16:05 rman_ts01.dbf -rw-r----- 1 oracle oinstall 671096832 Jul 16 16:26 sysaux01.dbf -rw-r----- 1 oracle oinstall 765468672 Jul 16 16:26 system01.dbf -rw-r----- 1 oracle oinstall 30416896 Jul 16 16:18 temp01.dbf -rw-r----- 1 oracle oinstall 2105344 Jul 16 16:26 testundotbs01.dbf -rw-r----- 1 oracle oinstall 120594432 Jul 16 16:05 undotbs01.dbf -rw-r----- 1 oracle oinstall 23601152 Jul 16 16:05 users01.dbf 11203ora-> rm -rf testundotbs01.dbf 11203ora-> ll total 2616356 -rw-r----- 1 oracle oinstall 9814016 Jul 16 16:27 control01.ctl -rw-r----- 1 oracle oinstall 209723392 Jul 16 16:05 DATACENTER01.dbf -rw-r----- 1 oracle oinstall 362422272 Jul 16 16:05 example01.dbf -rw-r----- 1 oracle oinstall 120594432 Jul 16 16:26 myundotbs01.dbf -rw-r----- 1 oracle oinstall 52429312 Jul 15 22:00 redo01.log -rw-r----- 1 oracle oinstall 52429312 Jul 16 16:00 redo02.log -rw-r----- 1 oracle oinstall 52429312 Jul 16 16:26 redo03.log -rw-r----- 1 oracle oinstall 209723392 Jul 16 16:05 rman_ts01.dbf -rw-r----- 1 oracle oinstall 671096832 Jul 16 16:26 sysaux01.dbf -rw-r----- 1 oracle oinstall 765468672 Jul 16 16:26 system01.dbf -rw-r----- 1 oracle oinstall 30416896 Jul 16 16:18 temp01.dbf -rw-r----- 1 oracle oinstall 120594432 Jul 16 16:05 undotbs01.dbf -rw-r----- 1 oracle oinstall 23601152 Jul 16 16:05 users01.dbf 11203ora->
SQL> drop tablespace testundotbs including contents and datafiles; Tablespace dropped. SQL>
切换undo tablespace
SQL> alter system set undo_tablespace=testundotbs; System altered. SQL> show parameter undo NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ undo_management string AUTO undo_retention integer 900 undo_tablespace string TESTUNDOTBS SQL>
little demo
将undo tablespace设置很小(2M),往表中插入超过2M的数据，会出现什么结果?
result:ora-30036
SQL> create undo tablespace testundotbs datafile '/u01/app/oracle/oradata/testdb/testundotbs01.dbf' size 2M autoextend off; Tablespace created.
SQL> select tablespace_name,status,contents from dba_tablespaces; TABLESPACE_NAME STATUS CONTENTS ------------------------------ --------- --------- SYSTEM ONLINE PERMANENT SYSAUX ONLINE PERMANENT UNDOTBS1 ONLINE UNDO TEMP ONLINE TEMPORARY USERS ONLINE PERMANENT EXAMPLE ONLINE PERMANENT APP_FGPS ONLINE PERMANENT RMAN_TS ONLINE PERMANENT MYUNDOTBS ONLINE UNDO TESTUNDOTBS ONLINE UNDO 10 rows selected.
SQL> alter system set undo_tablespace=testundotbs; System altered.
SQL> show parameter undo NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ undo_management string AUTO undo_retention integer 900 undo_tablespace string TESTUNDOTBS
SQL> show user USER is "HR" SQL> select * from t; ID NAME ---------- -------------------- 0 arcerzhang SQL> truncate table t; Table truncated. SQL> select * from t; no rows selected SQL> begin 2 for i in 1..1000000 3 loop 4 insert into t values(i,'arcerzhang'); 5 end loop; 6 end; 7 / begin * ERROR at line 1: ORA-30036: unable to extend segment by 8 in undo tablespace 'TESTUNDOTBS' ORA-06512: at line 4
little demo
由于undo tablespace size过小，导致查询失败；ora-01555错误;
看图通晓原理
关于undo tablespace size的调整
SQL> select max(undoblks / ((end_time - begin_time)*24*3600)) from v$undostat; MAX(UNDOBLKS/((END_TIME-BEGIN_TIME)*24*3600)) --------------------------------------------- 2.08833333 SQL>
SQL> select sum(undoblks) / sum((end_time - begin_time)*24*3600) from v$undostat; SUM(UNDOBLKS)/SUM((END_TIME-BEGIN_TIME)*24*3600) ------------------------------------------------ .062157134 SQL>
- Determining a size for the UNDO tablespace requires three pieces of information:
- (UR)UNDO_RETENTION in seconds
- (UPS)Number of undo data blocks generated per second
- (DBS)Overhead varies based on extent and file size(db_block_size)
计算undo tablespace size的方法一(最大值算法)：参数1 * 参数2 * 参数3
SQL> select max(undoblks / ((end_time - begin_time)*24*3600)) from v$undostat; MAX(UNDOBLKS/((END_TIME-BEGIN_TIME)*24*3600)) --------------------------------------------- 2.08833333
SQL> show parameter undo_retention NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ undo_retention integer 900 SQL>
SQL> show parameter db_block_size NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ db_block_size integer 8192
计算undo tablespace size的方法二(平均值算法)：参数1 * 参数2 * 参数3
SQL> select sum(undoblks) / sum((end_time - begin_time)*24*3600) from v$undostat; SUM(UNDOBLKS)/SUM((END_TIME-BEGIN_TIME)*24*3600) ------------------------------------------------ .062157134
SQL> show parameter undo_retention NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ undo_retention integer 900 SQL>
SQL> show parameter db_block_size NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ db_block_size integer 8192
undo tablespace quota-使用undo tablepsace quota来进行undo tablespace的管理
背景:undo tablespace事关全局，每个用户不可能在一个时间点占用全部的undo tablespace,这就牵扯到undo tablespace quota的问题.对于undo tablespace quota的问题，主要与undo_pool参数有关，属于resource manager中的内容；
•Long transactions and improperly written transactions can consume valuable resources.
•With undo quota,users can be grouped and a maximum undo space limit can be assigned to the group.
•UNDO_POOL,a Resource Manager directive,defines the amount of space allowed for a resource group.
•When a group exceeds its limit,no new transactions are possible for the group,until undo space is freed by current transactio which are either completing or aborting.
undo segment可以被多个transaction所共享；
Get Undo Segment Info
- Information about undo segments can be obtained by querying the following views: ---DBA_ROLLBACK_SEGS
-
View Code
SQL> select segment_name,tablespace_name from dba_rollback_segs; SEGMENT_NAME TABLESPACE_NAME ------------------------------ ------------------------------ SYSTEM SYSTEM _SYSSMU10_3271578125$ UNDOTBS1 _SYSSMU9_3945653786$ UNDOTBS1 _SYSSMU8_3612859353$ UNDOTBS1 _SYSSMU7_4222772309$ UNDOTBS1 _SYSSMU6_3654194381$ UNDOTBS1 _SYSSMU5_4011504098$ UNDOTBS1 _SYSSMU4_1126976075$ UNDOTBS1 _SYSSMU3_4004931649$ UNDOTBS1 _SYSSMU2_111974964$ UNDOTBS1 _SYSSMU1_1240252155$ UNDOTBS1 SEGMENT_NAME TABLESPACE_NAME ------------------------------ ------------------------------ _SYSSMU20_383735042$ MYUNDOTBS _SYSSMU19_3345254938$ MYUNDOTBS _SYSSMU18_1415882764$ MYUNDOTBS _SYSSMU17_3557938328$ MYUNDOTBS _SYSSMU16_1859217099$ MYUNDOTBS _SYSSMU15_1154943744$ MYUNDOTBS _SYSSMU14_1909609757$ MYUNDOTBS _SYSSMU13_3542379076$ MYUNDOTBS _SYSSMU12_1217287258$ MYUNDOTBS _SYSSMU11_1756135178$ MYUNDOTBS _SYSSMU28_3554829085$ TESTUNDOTBS SEGMENT_NAME TABLESPACE_NAME ------------------------------ ------------------------------ _SYSSMU27_2132966396$ TESTUNDOTBS _SYSSMU26_3800527619$ TESTUNDOTBS _SYSSMU25_1675500269$ TESTUNDOTBS _SYSSMU24_1510368484$ TESTUNDOTBS _SYSSMU23_2344035146$ TESTUNDOTBS _SYSSMU22_702459267$ TESTUNDOTBS _SYSSMU21_544576415$ TESTUNDOTBS 29 rows selected. SQL>
- Dynamic Performance Views
- V$ROLLNAME
-
View Code
SQL> select * from v$rollname; USN NAME ---------- ------------------------------ 0 SYSTEM 21 _SYSSMU21_544576415$ 22 _SYSSMU22_702459267$ 23 _SYSSMU23_2344035146$ 24 _SYSSMU24_1510368484$ 25 _SYSSMU25_1675500269$ 26 _SYSSMU26_3800527619$ 27 _SYSSMU27_2132966396$ 28 _SYSSMU28_3554829085$ 9 rows selected.
- V$ROLLSTAT(在线undo tablespace信息)
-
View Code
SQL> select usn,status from v$rollstat; USN STATUS ---------- --------------- 0 ONLINE 21 ONLINE 22 ONLINE 23 ONLINE 24 ONLINE 25 ONLINE 26 ONLINE 27 ONLINE 28 ONLINE 9 rows selected.
- V$UNDOSTAT
-
View Code
SQL> select begin_time,end_time,undoblks from v$undostat; BEGIN_TIME END_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/16 21:31:53 2013/07/16 21:36:01 4 2013/07/16 21:21:53 2013/07/16 21:31:53 17 2013/07/16 21:11:53 2013/07/16 21:21:53 13 2013/07/16 21:01:53 2013/07/16 21:11:53 14 2013/07/16 20:51:53 2013/07/16 21:01:53 48 2013/07/16 20:41:53 2013/07/16 20:51:53 13 2013/07/16 20:31:53 2013/07/16 20:41:53 20 2013/07/16 20:21:53 2013/07/16 20:31:53 14 2013/07/16 20:11:53 2013/07/16 20:21:53 13 2013/07/16 20:01:53 2013/07/16 20:11:53 22 2013/07/16 19:51:53 2013/07/16 20:01:53 43 BEGIN_TIME END_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/16 19:41:53 2013/07/16 19:51:53 11 2013/07/16 19:31:53 2013/07/16 19:41:53 14 2013/07/16 19:21:53 2013/07/16 19:31:53 14 2013/07/16 19:11:53 2013/07/16 19:21:53 15 2013/07/16 19:01:53 2013/07/16 19:11:53 14 2013/07/16 18:51:53 2013/07/16 19:01:53 47 2013/07/16 18:41:53 2013/07/16 18:51:53 13 2013/07/16 18:31:53 2013/07/16 18:41:53 14 2013/07/16 18:21:53 2013/07/16 18:31:53 16 2013/07/16 18:11:53 2013/07/16 18:21:53 18 2013/07/16 18:01:53 2013/07/16 18:11:53 15 BEGIN_TIME END_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/16 17:51:53 2013/07/16 18:01:53 48 2013/07/16 17:41:53 2013/07/16 17:51:53 14 2013/07/16 17:31:53 2013/07/16 17:41:53 13 2013/07/16 17:21:53 2013/07/16 17:31:53 17 2013/07/16 17:11:53 2013/07/16 17:21:53 16 2013/07/16 17:01:53 2013/07/16 17:11:53 18 2013/07/16 16:51:53 2013/07/16 17:01:53 48 2013/07/16 16:41:53 2013/07/16 16:51:53 14 2013/07/16 16:31:53 2013/07/16 16:41:53 31 2013/07/16 16:21:53 2013/07/16 16:31:53 17 2013/07/16 16:11:53 2013/07/16 16:21:53 18 BEGIN_TIME END_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/16 16:01:53 2013/07/16 16:11:53 13 2013/07/16 15:51:53 2013/07/16 16:01:53 111 2013/07/16 15:41:53 2013/07/16 15:51:53 13 2013/07/16 15:31:53 2013/07/16 15:41:53 18 2013/07/16 15:21:53 2013/07/16 15:31:53 12 2013/07/16 15:11:53 2013/07/16 15:21:53 16 2013/07/16 15:01:53 2013/07/16 15:11:53 17 2013/07/16 14:51:53 2013/07/16 15:01:53 116 2013/07/16 14:41:53 2013/07/16 14:51:53 13 2013/07/16 14:31:53 2013/07/16 14:41:53 15 2013/07/16 14:21:53 2013/07/16 14:31:53 13 BEGIN_TIME END_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/16 14:11:53 2013/07/16 14:21:53 16 2013/07/16 14:01:53 2013/07/16 14:11:53 20 2013/07/16 13:51:53 2013/07/16 14:01:53 101 2013/07/16 13:41:53 2013/07/16 13:51:53 15 2013/07/16 13:31:53 2013/07/16 13:41:53 15 2013/07/16 13:21:53 2013/07/16 13:31:53 13 2013/07/16 13:11:53 2013/07/16 13:21:53 17 2013/07/16 13:01:53 2013/07/16 13:11:53 16 2013/07/16 12:51:53 2013/07/16 13:01:53 115 2013/07/16 12:41:53 2013/07/16 12:51:53 14 2013/07/16 12:31:53 2013/07/16 12:41:53 15 BEGIN_TIME END_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/16 12:21:53 2013/07/16 12:31:53 14 2013/07/16 12:11:53 2013/07/16 12:21:53 17 2013/07/16 12:01:53 2013/07/16 12:11:53 12 2013/07/16 11:51:53 2013/07/16 12:01:53 160 2013/07/16 11:41:53 2013/07/16 11:51:53 13 2013/07/16 11:31:53 2013/07/16 11:41:53 25 2013/07/16 11:21:53 2013/07/16 11:31:53 12 2013/07/16 11:11:53 2013/07/16 11:21:53 17 2013/07/16 11:01:53 2013/07/16 11:11:53 15 2013/07/16 10:51:53 2013/07/16 11:01:53 97 2013/07/16 10:41:53 2013/07/16 10:51:53 17 BEGIN_TIME END_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/16 10:31:53 2013/07/16 10:41:53 12 2013/07/16 10:21:53 2013/07/16 10:31:53 15 2013/07/16 10:11:53 2013/07/16 10:21:53 18 2013/07/16 10:01:53 2013/07/16 10:11:53 12 2013/07/16 09:51:53 2013/07/16 10:01:53 121 2013/07/16 09:41:53 2013/07/16 09:51:53 16 2013/07/16 09:31:53 2013/07/16 09:41:53 18 2013/07/16 09:21:53 2013/07/16 09:31:53 19 2013/07/16 09:11:53 2013/07/16 09:21:53 13 2013/07/16 09:01:53 2013/07/16 09:11:53 18 2013/07/16 08:51:53 2013/07/16 09:01:53 83 BEGIN_TIME END_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/16 08:41:53 2013/07/16 08:51:53 16 2013/07/16 08:31:53 2013/07/16 08:41:53 14 2013/07/16 08:21:53 2013/07/16 08:31:53 13 2013/07/16 08:11:53 2013/07/16 08:21:53 13 2013/07/16 08:01:53 2013/07/16 08:11:53 11 2013/07/16 07:51:53 2013/07/16 08:01:53 109 2013/07/16 07:41:53 2013/07/16 07:51:53 13 2013/07/16 07:31:53 2013/07/16 07:41:53 14 2013/07/16 07:21:53 2013/07/16 07:31:53 21 2013/07/16 07:11:53 2013/07/16 07:21:53 14 2013/07/16 07:01:53 2013/07/16 07:11:53 13 BEGIN_TIME END_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/16 06:51:53 2013/07/16 07:01:53 91 2013/07/16 06:41:53 2013/07/16 06:51:53 12 2013/07/16 06:31:53 2013/07/16 06:41:53 16 2013/07/16 06:21:53 2013/07/16 06:31:53 15 2013/07/16 06:11:53 2013/07/16 06:21:53 16 2013/07/16 06:01:53 2013/07/16 06:11:53 13 2013/07/16 05:51:53 2013/07/16 06:01:53 101 2013/07/16 05:41:53 2013/07/16 05:51:53 13 2013/07/16 05:31:53 2013/07/16 05:41:53 14 2013/07/16 05:21:53 2013/07/16 05:31:53 18 2013/07/16 05:11:53 2013/07/16 05:21:53 12 BEGIN_TIME END_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/16 05:01:53 2013/07/16 05:11:53 10 2013/07/16 04:51:53 2013/07/16 05:01:53 111 2013/07/16 04:41:53 2013/07/16 04:51:53 15 2013/07/16 04:31:53 2013/07/16 04:41:53 14 2013/07/16 04:21:53 2013/07/16 04:31:53 12 2013/07/16 04:11:53 2013/07/16 04:21:53 19 2013/07/16 04:01:53 2013/07/16 04:11:53 16 2013/07/16 03:51:53 2013/07/16 04:01:53 92 2013/07/16 03:41:53 2013/07/16 03:51:53 15 2013/07/16 03:31:53 2013/07/16 03:41:53 14 2013/07/16 03:21:53 2013/07/16 03:31:53 14 BEGIN_TIME END_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/16 03:11:53 2013/07/16 03:21:53 15 2013/07/16 03:01:53 2013/07/16 03:11:53 15 2013/07/16 02:51:53 2013/07/16 03:01:53 93 2013/07/16 02:41:53 2013/07/16 02:51:53 11 2013/07/16 02:31:53 2013/07/16 02:41:53 17 2013/07/16 02:21:53 2013/07/16 02:31:53 15 2013/07/16 02:11:53 2013/07/16 02:21:53 22 2013/07/16 02:01:53 2013/07/16 02:11:53 12 2013/07/16 01:51:53 2013/07/16 02:01:53 107 2013/07/16 01:41:53 2013/07/16 01:51:53 13 2013/07/16 01:31:53 2013/07/16 01:41:53 12 BEGIN_TIME END_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/16 01:21:53 2013/07/16 01:31:53 15 2013/07/16 01:11:53 2013/07/16 01:21:53 14 2013/07/16 01:01:53 2013/07/16 01:11:53 31 2013/07/16 00:51:53 2013/07/16 01:01:53 252 2013/07/16 00:41:53 2013/07/16 00:51:53 15 2013/07/16 00:31:53 2013/07/16 00:41:53 13 2013/07/16 00:21:53 2013/07/16 00:31:53 13 2013/07/16 00:11:53 2013/07/16 00:21:53 16 2013/07/16 00:01:53 2013/07/16 00:11:53 21 2013/07/15 23:51:53 2013/07/16 00:01:53 110 2013/07/15 23:41:53 2013/07/15 23:51:53 14 BEGIN_TIME END_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/15 23:31:53 2013/07/15 23:41:53 13 2013/07/15 23:21:53 2013/07/15 23:31:53 18 2013/07/15 23:11:53 2013/07/15 23:21:53 18 2013/07/15 23:01:53 2013/07/15 23:11:53 16 2013/07/15 22:51:53 2013/07/15 23:01:53 118 2013/07/15 22:41:53 2013/07/15 22:51:53 14 2013/07/15 22:31:53 2013/07/15 22:41:53 14 2013/07/15 22:21:53 2013/07/15 22:31:53 19 2013/07/15 22:11:53 2013/07/15 22:21:53 17 2013/07/15 22:01:53 2013/07/15 22:11:53 28 2013/07/15 21:51:53 2013/07/15 22:01:53 1253 BEGIN_TIME END_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/15 21:41:53 2013/07/15 21:51:53 17 2013/07/15 21:31:53 2013/07/15 21:41:53 10 2013/07/15 21:21:53 2013/07/15 21:31:53 13 2013/07/15 21:11:53 2013/07/15 21:21:53 16 2013/07/15 21:01:53 2013/07/15 21:11:53 12 2013/07/15 20:51:53 2013/07/15 21:01:53 89 2013/07/15 20:41:53 2013/07/15 20:51:53 14 2013/07/15 20:31:53 2013/07/15 20:41:53 13 2013/07/15 20:21:53 2013/07/15 20:31:53 12 2013/07/15 20:11:53 2013/07/15 20:21:53 15 2013/07/15 20:01:53 2013/07/15 20:11:53 14 BEGIN_TIME END_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/15 19:51:53 2013/07/15 20:01:53 94 2013/07/15 19:41:53 2013/07/15 19:51:53 17 2013/07/15 19:31:53 2013/07/15 19:41:53 13 2013/07/15 19:21:53 2013/07/15 19:31:53 16 2013/07/15 19:11:53 2013/07/15 19:21:53 18 2013/07/15 19:01:53 2013/07/15 19:11:53 14 2013/07/15 18:51:53 2013/07/15 19:01:53 93 2013/07/15 18:41:53 2013/07/15 18:51:53 14 2013/07/15 18:31:53 2013/07/15 18:41:53 12 2013/07/15 18:21:53 2013/07/15 18:31:53 19 2013/07/15 18:11:53 2013/07/15 18:21:53 16 BEGIN_TIME END_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/15 18:01:53 2013/07/15 18:11:53 11 2013/07/15 17:51:53 2013/07/15 18:01:53 95 2013/07/15 17:41:53 2013/07/15 17:51:53 12 2013/07/15 17:31:53 2013/07/15 17:41:53 13 2013/07/15 17:21:53 2013/07/15 17:31:53 14 2013/07/15 17:11:53 2013/07/15 17:21:53 14 2013/07/15 17:01:53 2013/07/15 17:11:53 10 2013/07/15 16:51:53 2013/07/15 17:01:53 118 2013/07/15 16:41:53 2013/07/15 16:51:53 11 2013/07/15 16:31:53 2013/07/15 16:41:53 17 2013/07/15 16:21:53 2013/07/15 16:31:53 16 BEGIN_TIME END_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/15 16:11:53 2013/07/15 16:21:53 19 2013/07/15 16:01:53 2013/07/15 16:11:53 12 2013/07/15 15:51:53 2013/07/15 16:01:53 92 2013/07/15 15:41:53 2013/07/15 15:51:53 16 2013/07/15 15:31:53 2013/07/15 15:41:53 13 2013/07/15 15:21:53 2013/07/15 15:31:53 13 2013/07/15 15:11:53 2013/07/15 15:21:53 15 2013/07/15 15:01:53 2013/07/15 15:11:53 14 2013/07/15 14:51:53 2013/07/15 15:01:53 109 2013/07/15 14:41:53 2013/07/15 14:51:53 14 2013/07/15 14:31:53 2013/07/15 14:41:53 14 BEGIN_TIME END_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/15 14:21:53 2013/07/15 14:31:53 12 2013/07/15 14:11:53 2013/07/15 14:21:53 15 2013/07/15 14:01:53 2013/07/15 14:11:53 12 2013/07/15 13:51:53 2013/07/15 14:01:53 94 2013/07/15 13:41:53 2013/07/15 13:51:53 18 2013/07/15 13:31:53 2013/07/15 13:41:53 12 2013/07/15 13:21:53 2013/07/15 13:31:53 17 2013/07/15 13:11:53 2013/07/15 13:21:53 14 2013/07/15 13:01:53 2013/07/15 13:11:53 12 2013/07/15 12:51:53 2013/07/15 13:01:53 101 2013/07/15 12:41:53 2013/07/15 12:51:53 16 BEGIN_TIME END_TIME UNDOBLKS ------------------- ------------------- ---------- 2013/07/15 12:31:53 2013/07/15 12:41:53 12 2013/07/15 12:21:53 2013/07/15 12:31:53 15 2013/07/15 12:11:53 2013/07/15 12:21:53 16 2013/07/15 12:01:53 2013/07/15 12:11:53 87 2013/07/15 11:51:53 2013/07/15 12:01:53 22 203 rows selected. SQL>
- V$SESSION(常规)
- V$TRANSACTION(常规)
数据库的记录先写到log然后写到datafile，这样的话就存在一些redo已经写到logfile但是还没有写到datafile内，log中存储了transaction信息，包括commited or uncommited data。可能这些修改信息并没有被oracle正确的来处理，包含两种情况：已经提交的还没有写入数据文件，或者没有提交的却被写入了数据文件。此时如果instance crash了，在实例恢复时针对已经提交的还没有写入数据文件就要发生前滚，在前滚过程中，smon会根据online redo log中的记录来完成对datafile的修改。保证已经提交的数据写入数据文件datafile。
接下来，前滚结束后，数据库正常open，此时用户可以正常连接，可以访问已经recover的commited data，但是对于那些属于unrecoverable transaction的uncommited data，会被oracle 加锁，是不可以访问的。rolling back：假如有进程访问这些加锁的data，此时smon会对这些数据块做rollback回滚，从数据文件中撤销没有提交却被写入数据文件的数据。
/*如何实现undo segments and space 的自动化管理*/
1、创建一个undo_tablespace,名称为undo_tbs1
2、设置参数undo_tablespace
SQL> show parameter undo_tabl NAME TS Type VALUE ------------------------------------ ------------ ------------------------------ undo_tablespace string UNDOTBS1
3、设置参数undo_management
SQL> show parameter undo_manage NAME TS Type VALUE ------------------------------------ ------------ ------------------------------ undo_management string AUTO
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