《Oracle从入门到精通》读书笔记第八章 管理表空间和数据文件之二

8.5 管理undo表空间8.5.1 undo表空间的作用1、使读写一致2、可以回滚事物3、事物恢复4、闪回操作
8.5.2 undo表空间的初始化参数1、undo_tablespace：指定要使用的undo表空间2、undo_management：指定undo数据的管理模式，如果为auto，则为自动撤销管理模式，为manual，则为回滚段管理模式3、undo_retention：控制undo数据的最大保留时间，默认为900sSQL> col name for a20;SQL> col type for a10;SQL> col value for a20;SQL> show parameter undo_tablespace;NAME TYPE VALUE------------------------------------ ---------- ------------------------------undo_tablespace string UNDOTBS1SQL> show parameter undo_management;NAME TYPE VALUE------------------------------------ ---------- ------------------------------undo_management string AUTOSQL> show parameter undo_retention;NAME TYPE VALUE------------------------------------ ---------- ------------------------------undo_retention integer 900
8.5.3 撤销表空间的基本操作1、创建undo表空间需要注意一下两个方面：a、undo表空间对应的数据文件大小通常由DML操作可能产生的最大数据量来确定，通常该数据文件的大小至少为1G；b、undo表空间只用于存储撤销数据，不要再undo表空间内建立任何数据对象SQL> col tablespace_name for a10;SQL> col file_name for a50;SQL> col bytes for 999,999,999;SQL> select tablespace_name,file_name,bytes from dba_data_files order by tablespace_name;TABLESPACE FILE_NAME BYTES---------- -------------------------------------------------- ------------EXAMPLE /ora/app/oracle/oradata/stone1/example01.dbf 104,857,600SYSAUX /ora/app/oracle/oradata/stone1/sysaux01.dbf 555,745,280SYSTEM /ora/app/oracle/oradata/stone1/system01.dbf 713,031,680TBS_BIG /ora/app/oracle/oradata/stone1/datafilebig.dbf 20,971,520TBS_TEST_1 /ora/app/oracle/oradata/stone1/datafile1.dbf 10,485,760TBS_TEST_2 /ora/app/oracle/oradata/stone1/datafile2.dbf 10,485,760TBS_TEST_3 /ora/app/oracle/oradata/stone1/datafile3.dbf 10,485,760TBS_TEST_4 /ora/app/oracle/oradata/stone1/datafile4.dbf 20,971,520UNDOTBS1 /ora/app/oracle/oradata/stone1/undotbs01.dbf 89,128,960USERS /ora/app/oracle/oradata/stone1/users01.dbf 5,242,88010 rows selected.SQL> create undo tablespace undo_test1 2 datafile '/ora/app/oracle/oradata/stone1/undo_test1.dbf' 3 size 10m;Tablespace created.SQL> select tablespace_name,file_name,bytes from dba_data_files order by tablespace_name;TABLESPACE FILE_NAME BYTES---------- -------------------------------------------------- ------------EXAMPLE /ora/app/oracle/oradata/stone1/example01.dbf 104,857,600SYSAUX /ora/app/oracle/oradata/stone1/sysaux01.dbf 555,745,280SYSTEM /ora/app/oracle/oradata/stone1/system01.dbf 713,031,680TBS_BIG /ora/app/oracle/oradata/stone1/datafilebig.dbf 20,971,520TBS_TEST_1 /ora/app/oracle/oradata/stone1/datafile1.dbf 10,485,760TBS_TEST_2 /ora/app/oracle/oradata/stone1/datafile2.dbf 10,485,760TBS_TEST_3 /ora/app/oracle/oradata/stone1/datafile3.dbf 10,485,760TBS_TEST_4 /ora/app/oracle/oradata/stone1/datafile4.dbf 20,971,520UNDOTBS1 /ora/app/oracle/oradata/stone1/undotbs01.dbf 89,128,960UNDO_TEST1 /ora/app/oracle/oradata/stone1/undo_test1.dbf 10,485,760USERS /ora/app/oracle/oradata/stone1/users01.dbf 5,242,88011 rows selected.
2、修改undo表空间SQL> alter tablespace undo_test1 2 add datafile '/ora/app/oracle/oradata/stone1/undo_test2.dbf' 3 size 10m;Tablespace altered.SQL> select tablespace_name,file_name,bytes from dba_data_files order by tablespace_name;TABLESPACE FILE_NAME BYTES---------- -------------------------------------------------- ------------EXAMPLE /ora/app/oracle/oradata/stone1/example01.dbf 104,857,600SYSAUX /ora/app/oracle/oradata/stone1/sysaux01.dbf 555,745,280SYSTEM /ora/app/oracle/oradata/stone1/system01.dbf 713,031,680TBS_BIG /ora/app/oracle/oradata/stone1/datafilebig.dbf 20,971,520TBS_TEST_1 /ora/app/oracle/oradata/stone1/datafile1.dbf 10,485,760TBS_TEST_2 /ora/app/oracle/oradata/stone1/datafile2.dbf 10,485,760TBS_TEST_3 /ora/app/oracle/oradata/stone1/datafile3.dbf 10,485,760TBS_TEST_4 /ora/app/oracle/oradata/stone1/datafile4.dbf 20,971,520UNDOTBS1 /ora/app/oracle/oradata/stone1/undotbs01.dbf 89,128,960UNDO_TEST1 /ora/app/oracle/oradata/stone1/undo_test2.dbf 10,485,760UNDO_TEST1 /ora/app/oracle/oradata/stone1/undo_test1.dbf 10,485,760TABLESPACE FILE_NAME BYTES---------- -------------------------------------------------- ------------USERS /ora/app/oracle/oradata/stone1/users01.dbf 5,242,88012 rows selected.
3、切换undo表空间oracle 11g默认的undo表空间是undotbs1SQL> alter system set undo_tablespace=undo_test1;System altered.SQL> show parameter undo_tablespace;NAME TYPE VALUE------------------------------------ ---------- ------------------------------undo_tablespace string UNDO_TEST1
4、删除undo表空间SQL> alter system set undo_tablespace=undotbs1;System altered.SQL> drop tablespace undo_test1;Tablespace dropped.SQL> show parameter undo_tablespace;NAME TYPE VALUE------------------------------------ ---------- ------------------------------undo_tablespace string UNDOTBS1SQL> select tablespace_name,file_name,bytes from dba_data_files order by tablespace_name;TABLESPACE FILE_NAME BYTES---------- -------------------------------------------------- ------------EXAMPLE /ora/app/oracle/oradata/stone1/example01.dbf 104,857,600SYSAUX /ora/app/oracle/oradata/stone1/sysaux01.dbf 555,745,280SYSTEM /ora/app/oracle/oradata/stone1/system01.dbf 713,031,680TBS_BIG /ora/app/oracle/oradata/stone1/datafilebig.dbf 20,971,520TBS_TEST_1 /ora/app/oracle/oradata/stone1/datafile1.dbf 10,485,760TBS_TEST_2 /ora/app/oracle/oradata/stone1/datafile2.dbf 10,485,760TBS_TEST_3 /ora/app/oracle/oradata/stone1/datafile3.dbf 10,485,760TBS_TEST_4 /ora/app/oracle/oradata/stone1/datafile4.dbf 20,971,520UNDOTBS1 /ora/app/oracle/oradata/stone1/undotbs01.dbf 89,128,960USERS /ora/app/oracle/oradata/stone1/users01.dbf 5,242,88010 rows selected.
5、查询undo表空间信息（1）当前实例正在使用的undo表空间查询初始化参数undo_tablespacesSQL> show parameter undo_tablespace;NAME TYPE VALUE------------------------------------ ---------- ------------------------------undo_tablespace string UNDOTBS1
（2）实例的所有undo表空间查询数据字典dba_tablespacesSQL> select tablespace_name as name from dba_tablespaces where contents='UNDO';NAME--------------------UNDOTBS1
（3）undo表空间的统计信息在数据库运行高峰期搜集undo表空间的统计信息，根据统计信息确定undo表空间的大小查询动态性能视图v$undostatSQL> select to_char(begin_time,'hh24:mi:ss') as BeginTime, 2 to_char(end_time,'hh24:mi:ss') as EndTime, 3 undoblks as numbers 4 from v$undostat 5 order by begin_time;BEGINTIME ENDTIME NUMBERS------------------------ ------------------------ ----------20:19:49 20:29:49 320:29:49 20:39:49 5520:39:49 20:49:49 120:49:49 20:59:16 1
（4）显示undo段统计信息使用自动undo管理模式时，oracle会在undo表空间上自动建立10个undo段查询动态性能视图v$rollname显示所有联机undo段的名称查询动态性能视图v$rollstat显示undo段的统计信息
SQL> select rn.name,rs.xacts,rs.writes,rs.extents 2 from v$rollname rn,v$rollstat rs 3 where rn.usn=rs.usn;NAME XACTS WRITES EXTENTS-------------------- ---------- ---------- ----------SYSTEM 0 46174 6_SYSSMU1_3780397527$ 0 14538 4_SYSSMU2_2232571081$ 0 39166 5_SYSSMU3_2097677531$ 0 71240 7_SYSSMU4_1152005954$ 0 18086 5_SYSSMU5_1527469038$ 0 17184 6_SYSSMU6_2443381498$ 0 20054 5_SYSSMU7_3286610060$ 0 30472 5_SYSSMU8_2012382730$ 0 17480 7_SYSSMU9_1424341975$ 0 156986 6_SYSSMU10_3550978943 0 17594 4NAME XACTS WRITES EXTENTS-------------------- ---------- ---------- ----------$11 rows selected.
name：标识undo段的名称xacts：标识undo段所包含的活动事物个数writers：标识在undo段写入的字节数extents：标识undo段的区个数
（5）显示活动事物信息使用动态性能视图v$session显示会话的详细信息使用动态性能视图v$transaction显示事物的详细信息SQL> select name,status from v$transaction;no rows selected
（6）显示undo区信息在数据字典dba_undo_extents中，用户可以查询undo表空间中所有区得详细信息，包括undo区的大小和状态等信息SQL> desc dba_undo_extents; Name Null? Type ----------------------------------------- -------- ---------------------------- OWNER CHAR(3) SEGMENT_NAME NOT NULL VARCHAR2(30) TABLESPACE_NAME NOT NULL VARCHAR2(30) EXTENT_ID NUMBER FILE_ID NOT NULL NUMBER BLOCK_ID NUMBER BYTES NUMBER BLOCKS NUMBER RELATIVE_FNO NUMBER COMMIT_JTIME NUMBER COMMIT_WTIME VARCHAR2(20) STATUS VARCHAR2(9)
8.6 管理临时表空间8.6.1 临时表空间概述主要用于内存排序区不够而必须将数据写到磁盘的那个逻辑区域下面几种操作经常会经常用的临时表空间：select distinct不重复检索union 联合查询minus计算analyze分析连接两个没有索引的表
8.6.2 创建临时表空间SQL> create temporary tablespace temp_01 2 tempfile '/ora/app/oracle/oradata/stone1/temp_01.tbf' 3 size 10m;Tablespace created.SQL> alter database default temporary tablespace temp_01;Database altered.
8.6.3 查询临时表空间信息临时表空间信息存放在dba_temp_files中在v$tempfiles中可以查看临时表空间的使用情况SQL> col file_name for a50;SQL> col tablespace_name for a20;SQL> show linesize;linesize 80SQL> set linesize 100;SQL> show linesize;linesize 100SQL> select file_name,tablespace_name,bytes from dba_temp_files;FILE_NAME TABLESPACE_NAME BYTES-------------------------------------------------- -------------------- ------------/ora/app/oracle/oradata/stone1/temp01.dbf TEMP 30,408,704/ora/app/oracle/oradata/stone1/temp_01.tbf TEMP_01 10,485,760
8.6.4 关于临时表空间组作用：a、避免因大量排序数据导致单一临时表空间不足b、一个用户有多个会话时，可以使用组中的不同临时表空间c、使并行的服务器在单节点上使用多个临时表空间
1、创建临时表空间组SQL> col name for a10;SQL> select tablespace_name as name,file_name,bytes from dba_temp_files;NAME FILE_NAME BYTES---------- -------------------------------------------------- ------------TEMP /ora/app/oracle/oradata/stone1/temp01.dbf 30,408,704TEMP_01 /ora/app/oracle/oradata/stone1/temp_01.tbf 10,485,760SQL> create temporary tablespace tp1 2 tempfile '/ora/app/oracle/oradata/stone1/tp1.tpf' 3 size 10m 4 tablespace group group1;Tablespace created.SQL> create temporary tablespace tp2 2 tempfile '/ora/app/oracle/oradata/stone1/tp2.tpf' 3 size 10m 4 tablespace group group1;Tablespace created.SQL> select tablespace_name as name,file_name,bytes from dba_temp_files;NAME FILE_NAME BYTES---------- -------------------------------------------------- ------------TEMP /ora/app/oracle/oradata/stone1/temp01.dbf 30,408,704TEMP_01 /ora/app/oracle/oradata/stone1/temp_01.tbf 10,485,760TP1 /ora/app/oracle/oradata/stone1/tp1.tpf 10,485,760TP2 /ora/app/oracle/oradata/stone1/tp2.tpf 10,485,760
2、转移临时表空间到另一个组SQL> create temporary tablespace tp3 2 tempfile '/ora/app/oracle/oradata/stone1/tp3.tpf' 3 size 10m 4 tablespace group group3;Tablespace created.
SQL> col group_name for a15;SQL> select * from dba_tablespace_groups;GROUP_NAME TABLESPACE_NAME--------------- --------------------GROUP1 TP1GROUP1 TP2GROUP3 TP3
SQL> alter tablespace tp1 tablespace group group3;Tablespace altered.SQL> select * from dba_tablespace_groups;GROUP_NAME TABLESPACE_NAME--------------- --------------------GROUP3 TP1GROUP1 TP2GROUP3 TP3
3、把临时表空间组分配给指定的用户使用SQL> alter user scott temporary tablespace group3;User altered.
4、设置默认的临时表空间组SQL> alter database stone1 default temporary tablespace group3;Database altered.
SQL> alter database stone1 default temporary tablespace temp;Database altered.

5、删除临时表空间组SQL> drop tablespace tp1 including contents and datafiles;Tablespace dropped.SQL> select * from dba_tablespace_groups;GROUP_NAME TABLESPACE_NAME--------------- --------------------GROUP1 TP2GROUP3 TP3SQL> drop tablespace tp3 including contents and datafiles;Tablespace dropped.SQL> select * from dba_tablespace_groups;GROUP_NAME TABLESPACE_NAME--------------- --------------------GROUP1 TP2本文出自 “石头记” 博客，请务必保留此出处http://stonebox.blog.51cto.com/5409313/1357962