1.关于heartbeat和checkpoint
在这次的删除过程中我没有执行commit，而是直接abort数据库。整个删除过程执行了近6分钟，控制文件的心跳每三秒进行一次，心跳是把low cache rba记录到了控制文件中，而没有真正的把全部的脏数据写入到磁盘( 只有发生了checkpoint时候，才会把相关的脏数据写入到磁盘，而这里的控制文件的heartbeat和checkpoint是两回事，checkpoint一般是在切换日志，数据文件正常离线，执行begin backup命令时发生，昨晚晚上后面的一个困惑就是上面的英文描述，让我把这两者搞混淆了)
2.三种rba解释
low rba ：在buffer cache中的数据块第一次数据改变所对应的RAB。
high rba ：在buffer cache中的数据块最近一次数据改变时所对应的RAB。
on-disk rba：是 lgwr 写日志文件的最末位置的地址。
3.实例恢复过程解释
实例恢复的时候，是从控制文件heartbeat记录的low rba开始读redo log数据(会多读取一点，因为heartbeat是每三秒执行一次，假设在2.9秒的时候，数据库异常down了，控制文件中记录的还是2.9秒前的low rba，这个时候，从该点开始读取redo),恢复到on-disk rba，而不是high rba(high rba一般情况下会大于on-disk rba,但是因为high rba比on-disk rba多的部分记录在redo log buffer中，在实例恢复的时候，因为其未被记录到redo log file中，所以不能被恢复，其实也没有必要恢复，因为该数据肯定是没有commit或者rollback)
具体内容和实验请见:RBA和实例恢复关系
Author Archives: 惜分飞
ORA-600 kcratr_nab_less_than_odr故障解决
朋友的数据库服务器出现ORA-00600[kcratr_nab_less_than_odr]，不能open数据库
1.open数据库报ORA-00600[kcratr_nab_less_than_odr]
SQL> ALTER DATABASE OPEN; ALTER DATABASE OPEN * 第 1 行出现错误: ORA-00600: 内部错误代码, 参数: [kcratr_nab_less_than_odr], [1], [99189], [43531], [43569], [], [], [], [], [], [], []
2.查看alert日志
Wed Jan 11 13:56:16 2012 ALTER DATABASE OPEN Beginning crash recovery of 1 threads parallel recovery started with 2 processes Started redo scan Completed redo scan read 54591 KB redo, 0 data blocks need recovery Errors in file d:\dbdms\diag\rdbms\dbdms\dbdms\trace\dbdms_ora_3108.trc (incident=818557): ORA-00600: 内部错误代码, 参数: [kcratr_nab_less_than_odr], [1], [99189], [43531], [43569], [], [], [], [], [], [], [] Incident details in: d:\dbdms\diag\rdbms\dbdms\dbdms\incident\incdir_818557\dbdms_ora_3936_i818557.trc Aborting crash recovery due to error 600 Errors in file d:\dbdms\diag\rdbms\dbdms\dbdms\trace\dbdms_ora_3108.trc: ORA-00600: 内部错误代码, 参数: [kcratr_nab_less_than_odr], [1], [99189], [43531], [43569], [], [], [], [], [], [], [] Errors in file d:\dbdms\diag\rdbms\dbdms\dbdms\trace\dbdms_ora_3108.trc: ORA-00600: 内部错误代码, 参数: [kcratr_nab_less_than_odr], [1], [99189], [43531], [43569], [], [], [], [], [], [], [] ORA-600 signalled during: ALTER DATABASE OPEN... Trace dumping is performing id=[cdmp_20120110214555]
3.查看trace文件
Trace file d:\dbdms\diag\rdbms\dbdms\dbdms\trace\dbdms_ora_3108.trc Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production With the Partitioning, OLAP, Data Mining and Real Application Testing options Windows NT Version V6.1 Service Pack 1 CPU : 2 - type 8664, 2 Physical Cores Process Affinity : 0x0x0000000000000000 Memory (Avail/Total): Ph:2250M/4060M, Ph+PgF:5868M/8119M Instance name: dbdms Redo thread mounted by this instance: 1 Oracle process number: 17 Windows thread id: 3108, image: ORACLE.EXE (SHAD) ………………………… WARNING! Crash recovery of thread 1 seq 99189 is ending at redo block 43531 but should not have ended before redo block 43569 Incident 826550 created, dump file: d:\dbdms\diag\rdbms\dbdms\dbdms\incident\incdir_826550\dbdms_ora_3108_i826550.trc ORA-00600: ??????, ??: [kcratr_nab_less_than_odr], [1], [99189], [43531], [43569], [], [], [], [], [], [], [] ORA-00600: ??????, ??: [kcratr_nab_less_than_odr], [1], [99189], [43531], [43569], [], [], [], [], [], [], [] ORA-00600: ??????, ??: [kcratr_nab_less_than_odr], [1], [99189], [43531], [43569], [], [], [], [], [], [], []
通过alert和trace中的内容可以知道，数据库需要恢复到rba到43569，但是因为某种原因实例恢复的时候，只能利用1 thread 99189 seq#，恢复rba到43531。从而导致数据库无法正常open
This Problem is caused by Storage Problem of the Database Files. The Subsystem (eg. SAN) crashed while the Database was open. The Database then crashed since the Database Files were not accessible anymore. This caused a lost Write into the Online RedoLogs and so Instance Recovery is not possible and raising the ORA-600.
4.解决方法
SQL> SELECT STATUS FROM V$INSTANCE; STATUS ------------ MOUNTED --尝试直接recover database SQL> RECOVER DATABASE ; ORA-00283: 恢复会话因错误而取消 ORA-00264: 不要求恢复 --提示不用恢复 --再打开数据库，还是kcratr_nab_less_than_odr错误警告 SQL> ALTER DATABASE OPEN; ALTER DATABASE OPEN * 第 1 行出现错误: ORA-00600: 内部错误代码, 参数: [kcratr_nab_less_than_odr], [1], [99189], [43531], [43569], [], [], [], [], [], [], [] --尝试不完全恢复 SQL> RECOVER DATABASE UNTIL CANCEL; ORA-10879: error signaled in parallel recovery slave ORA-01547: 警告: RECOVER 成功但 OPEN RESETLOGS 将出现如下错误 ORA-01152: 文件 1 没有从过旧的备份中还原 ORA-01110: 数据文件 1: 'D:\DBDMS\DATA\SYSTEM01.DBF' --重建控制文件 SQL> ALTER DATABASE BACKUP CONTROLFILE TO TRACE AS 'D:/1.TXT'; 数据库已更改。 SQL> SHUTDOWN IMMEDIATE; ORA-01109: 数据库未打开 已经卸载数据库。 ORACLE 例程已经关闭。 SQL> STARTUP NOMOUNT; ORACLE 例程已经启动。 Total System Global Area 417546240 bytes Fixed Size 2176328 bytes Variable Size 268438200 bytes Database Buffers 138412032 bytes Redo Buffers 8519680 bytes SQL> CREATE CONTROLFILE REUSE DATABASE "DBDMS" NORESETLOGS NOARCHIVELOG 2 MAXLOGFILES 16 3 MAXLOGMEMBERS 3 4 MAXDATAFILES 100 5 MAXINSTANCES 8 6 MAXLOGHISTORY 18688 7 LOGFILE 8 GROUP 1 'D:\DBDMS\LOG\REDO01.LOG' SIZE 50M BLOCKSIZE 512, 9 GROUP 2 'D:\DBDMS\LOG\REDO02.LOG' SIZE 50M BLOCKSIZE 512, 10 GROUP 3 'D:\DBDMS\LOG\REDO03.LOG' SIZE 50M BLOCKSIZE 512 11 DATAFILE 12 'D:\DBDMS\DATA\SYSTEM01.DBF', 13 'D:\DBDMS\DATA\SYSAUX01.DBF', 14 'D:\DBDMS\DATA\RBSG01.DBF', 15 'D:\DBDMS\DATA\DATA01.DBF', 16 'D:\DBDMS\DATA\INDX01.DBF', 17 'D:\DBDMS\DATA\DATA02.DBF', 18 'D:\DBDMS\DATA\DATA03.DBF', 19 'D:\DBDMS\DATA\DATA04.DBF', 20 'D:\DBDMS\DATA\INDX02.DBF', 21 'D:\DBDMS\DATA\SYSTEM02.DBF' 22 CHARACTER SET ZHS16GBK 23 ; 控制文件已创建。 --继续尝试恢复 SQL> RECOVER DATABASE ; 完成介质恢复。 SQL> ALTER DATABASE OPEN; 数据库已更改。 --open成功
在这次恢复中，主要就是重建控制文件，然后直接恢复成功，如果redo有损坏，那么可能需要使用不完全恢复，然后使用resetlogs打开数据库
CAST本质探讨
1.试验前提
SQL> select * from v$version;
BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
PL/SQL Release 11.2.0.3.0 - Production
CORE 11.2.0.3.0 Production
TNS for Linux: Version 11.2.0.3.0 - Production
NLSRTL Version 11.2.0.3.0 - Production
SQL> select FORCE_LOGGING,SUPPLEMENTAL_LOG_DATA_PK,SUPPLEMENTAL_LOG_DATA_UI,
2 SUPPLEMENTAL_LOG_DATA_MIN from v$database;
FOR SUP SUP SUPPLEME
--- --- --- --------
NO NO NO NO
SQL> conn / as sysdba
Connected.
SQL> archive log list;
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /opt/oracle/oradata/archivelog/chf
Oldest online log sequence 1879
Next log sequence to archive 1881
Current log sequence 1881
SQL> select count(*) from t_xifenfei_move;
COUNT(*)
----------
7432085
SQL> select bytes/1024/1024 from user_segments where segment_name='T_XIFENFEI_MOVE';
BYTES/1024/1024
---------------
832
从上面信息可以看到数据库处于归档模式，强制日志和辅助日志为开启，试验测试表t_xifenfei_move有7432085条记录，占用硬盘空间832M
2.常规CAST
SQL> alter system flush buffer_cache;
System altered.
SQL> alter system flush shared_pool;
System altered.
SQL> SET TIMING ON
SQL> select a.name, b.value
2 from v$statname a, v$mystat b
3 where a.statistic# = b.statistic#
4 and lower(a.name) in
5 ('redo size','undo change vector size');
NAME VALUE
---------------------------------------------------------------- ----------
redo size 100028
undo change vector size 16172
Elapsed: 00:00:00.06
SQL> create table chf.t_xifenfei_move_CAST tablespace users
2 as
3 select * from chf.t_xifenfei_move;
Table created.
Elapsed: 00:01:58.10
SQL> select a.name, b.value
2 from v$statname a, v$mystat b
3 where a.statistic# = b.statistic#
4 and lower(a.name) in
5 ('redo size','undo change vector size');
NAME VALUE
---------------------------------------------------------------- ----------
redo size 873150548
undo change vector size 131384
Elapsed: 00:00:00.01
SQL> select 873150548-100028 "redo size" from dual;
redo size
----------
873050520
SQL> select 131384-16172 "undo size" from dual;
undo size
----------
115212
通过这个可以得出结论，产生redo为873050520，undo为115212
3.普通INSERT
SQL> alter system flush buffer_cache;
System altered.
Elapsed: 00:00:00.06
SQL> alter system flush shared_pool;
System altered.
Elapsed: 00:00:00.01
SQL> select a.name, b.value
2 from v$statname a, v$mystat b
3 where a.statistic# = b.statistic#
4 and lower(a.name) in
5 ('redo size','undo change vector size');
NAME VALUE
---------------------------------------------------------------- ----------
redo size 732
undo change vector size 136
Elapsed: 00:00:00.18
SQL> CREATE TABLE t_xifenfei_move_INSERT
2 AS
3 SELECT * FROM T_XIFENFEI_MOVE WHERE 1=0;
Table created.
Elapsed: 00:00:00.32
SQL> select a.name, b.value
2 from v$statname a, v$mystat b
3 where a.statistic# = b.statistic#
4 and lower(a.name) in
5 ('redo size','undo change vector size');
NAME VALUE
---------------------------------------------------------------- ----------
redo size 22712
undo change vector size 6512
Elapsed: 00:00:00.02
SQL> INSERT INTO t_xifenfei_move_INSERT
2 SELECT * FROM T_XIFENFEI_MOVE;
7432085 rows created.
Elapsed: 00:01:59.47
SQL> select a.name, b.value
2 from v$statname a, v$mystat b
3 where a.statistic# = b.statistic#
4 and lower(a.name) in
5 ('redo size','undo change vector size');
NAME VALUE
---------------------------------------------------------------- ----------
redo size 862261580
undo change vector size 27980508
--redo
SQL> select 22712-732 "create redo size" from dual;
create redo size
----------------
21980
SQL> select 862261580-22712 "insert redo size" from dual;
insert redo size
----------------
862238868
--undo
SQL> select 6512-136 "create undo size" from dual;
create undo size
----------------
6376
SQL> select 27980508-6512 "insert undo size" from dual;
insert undo size
----------------
27973996
通过这个可以得出CREATE TABLE 过程中产生redo:21980,undo:6376,而INSERT 过程中产生的redo:862238868,undo:27973996,整个过程总的产生redo:862260848(862238868+21980),undo:27980372(27973996+6376)
4.INSERT+APPEND
SQL> alter system flush buffer_cache;
System altered.
Elapsed: 00:00:25.19
SQL> alter system flush shared_pool;
System altered.
Elapsed: 00:00:00.04
SQL> select a.name, b.value
2 from v$statname a, v$mystat b
3 where a.statistic# = b.statistic#
4 and lower(a.name) in
5 ('redo size','undo change vector size');
NAME VALUE
---------------------------------------------------------------- ----------
redo size 732
undo change vector size 136
Elapsed: 00:00:00.05
SQL> create table chf.t_xifenfei_move_INSERT_A tablespace users
2 as
3 select * from chf.t_xifenfei_move where 1=0;
Table created.
Elapsed: 00:00:00.18
SQL> select a.name, b.value
2 from v$statname a, v$mystat b
3 where a.statistic# = b.statistic#
4 and lower(a.name) in
5 ('redo size','undo change vector size');
NAME VALUE
---------------------------------------------------------------- ----------
redo size 21892
undo change vector size 6308
Elapsed: 00:00:00.00
SQL> INSERT /*+ append */INTO t_xifenfei_move_INSERT_A
2 SELECT * FROM T_XIFENFEI_MOVE;
7432085 rows created.
Elapsed: 00:02:26.37
SQL> select a.name, b.value
2 from v$statname a, v$mystat b
3 where a.statistic# = b.statistic#
4 and lower(a.name) in
5 ('redo size','undo change vector size');
NAME VALUE
---------------------------------------------------------------- ----------
redo size 872792032
undo change vector size 87764
--redo
SQL> select 21892-732 "create redo size" from dual;
create redo size
----------------
21160
SQL> select 872792032-21892 "insert redo size" from dual;
insert redo size
----------------
872770140
--undo
SQL> select 6308-136 "create undo size" from dual;
create undo size
----------------
6172
SQL> select 87764-6308 "insert undo size" from dual;
insert undo size
----------------
81456
这个过程可以得到结论,create 表的过程产生的redo:21160,undo:6172;insert 表的过程redo:872770140,undo:81456;整个过程产生的redo:872791300(21160+872770140),undo:87628(6172+81456)
5.INSERT+NOLOGGING
SQL> alter system flush buffer_cache;
System altered.
Elapsed: 00:00:02.21
SQL> alter system flush shared_pool;
System altered.
Elapsed: 00:00:00.06
SQL> select a.name, b.value
2 from v$statname a, v$mystat b
3 where a.statistic# = b.statistic#
4 and lower(a.name) in
5 ('redo size','undo change vector size');
NAME VALUE
---------------------------------------------------------------- ----------
redo size 780
undo change vector size 136
Elapsed: 00:00:00.06
SQL> create table chf.t_xifenfei_move_INSERT_N tablespace users
2 as
3 select * from chf.t_xifenfei_move where 1=0;
Table created.
Elapsed: 00:00:00.22
SQL> select a.name, b.value
2 from v$statname a, v$mystat b
3 where a.statistic# = b.statistic#
4 and lower(a.name) in
5 ('redo size','undo change vector size');
NAME VALUE
---------------------------------------------------------------- ----------
redo size 22056
undo change vector size 6308
Elapsed: 00:00:00.00
SQL> INSERT /*+ NOLOGGING */INTO t_xifenfei_move_INSERT_N
2 SELECT * FROM T_XIFENFEI_MOVE;
7432085 rows created.
Elapsed: 00:02:30.33
SQL> select a.name, b.value
2 from v$statname a, v$mystat b
3 where a.statistic# = b.statistic#
4 and lower(a.name) in
5 ('redo size','undo change vector size');
NAME VALUE
---------------------------------------------------------------- ----------
redo size 862123984
undo change vector size 27982876
--redo
SQL> select 22056-780 "create redo size" from dual;
create redo size
----------------
21276
SQL> select 862123984-22056 "insert redo size" from dual;
insert redo size
----------------
862101928
--undo
SQL> select 6308-136 "create undo size" from dual;
create undo size
----------------
6172
SQL> select 27982876-6308 "insert undo size" from dual;
insert undo size
----------------
27976568
这个试验过程得出,create table得到redo:21276,undo:6172,insert table 得到redo:862101928,undo:27976568,整个过程redo:862123204,undo:27982740(27976568+6172)
6.INSERT+NOLOGGING(TABLE)
SQL> alter system flush buffer_cache;
System altered.
Elapsed: 00:00:23.68
SQL> alter system flush shared_pool;
System altered.
Elapsed: 00:00:00.04
SQL> select a.name, b.value
2 from v$statname a, v$mystat b
3 where a.statistic# = b.statistic#
4 and lower(a.name) in
5 ('redo size','undo change vector size');
NAME VALUE
---------------------------------------------------------------- ----------
redo size 800
undo change vector size 136
Elapsed: 00:00:00.18
SQL> create table chf.t_xifenfei_move_INSERT_N_new nologging tablespace users
2 as
3 select * from chf.t_xifenfei_move where 1=0;
Table created.
Elapsed: 00:00:00.71
SQL> select a.name, b.value
2 from v$statname a, v$mystat b
3 where a.statistic# = b.statistic#
4 and lower(a.name) in
5 ('redo size','undo change vector size');
NAME VALUE
---------------------------------------------------------------- ----------
redo size 23296
undo change vector size 6756
Elapsed: 00:00:00.00
SQL> INSERT INTO t_xifenfei_move_INSERT_N_new
2 SELECT * FROM T_XIFENFEI_MOVE;
7432085 rows created.
Elapsed: 00:02:37.51
SQL> select a.name, b.value
2 from v$statname a, v$mystat b
3 where a.statistic# = b.statistic#
4 and lower(a.name) in
5 ('redo size','undo change vector size');
NAME VALUE
---------------------------------------------------------------- ----------
redo size 862031304
undo change vector size 27982776
SQL> select 23296-800 "create redo size" from dual;
create redo size
----------------
22496
SQL> select 862031304-23296 "insert redo size" from dual;
insert redo size
----------------
862008008
SQL> select 6756-136 "create undo size" from dual;
create undo size
----------------
6620
SQL> select 27982776-6756 "insert undo size" from dual;
insert undo size
----------------
27976020
通过该试验得出,create table 产生redo:22496,undo:6620;insert into 产生redo:862008008,undo:27976020;整个过程产生redo:862030504(22496+862008008),undo:27982640(6620+27976020)
7.APPEND+NOLOGGING(TABLE)
SQL> alter system flush buffer_cache;
System altered.
Elapsed: 00:00:23.59
SQL> alter system flush shared_pool;
System altered.
Elapsed: 00:00:00.05
SQL> select a.name, b.value
2 from v$statname a, v$mystat b
3 where a.statistic# = b.statistic#
4 and lower(a.name) in
5 ('redo size','undo change vector size');
NAME VALUE
---------------------------------------------------------------- ----------
redo size 780
undo change vector size 136
Elapsed: 00:00:00.04
SQL> create table chf.t_xifenfei_move_INSERT_NA nologging tablespace users
2 as
3 select * from chf.t_xifenfei_move where 1=0;
Table created.
Elapsed: 00:00:00.42
SQL> select a.name, b.value
2 from v$statname a, v$mystat b
3 where a.statistic# = b.statistic#
4 and lower(a.name) in
5 ('redo size','undo change vector size');
NAME VALUE
---------------------------------------------------------------- ----------
redo size 22000
undo change vector size 6308
Elapsed: 00:00:00.00
SQL> INSERT /*+APPEND */ INTO t_xifenfei_move_INSERT_NA
2 SELECT * FROM T_XIFENFEI_MOVE;
7432085 rows created.
Elapsed: 00:01:08.92
SQL> select a.name, b.value
2 from v$statname a, v$mystat b
3 where a.statistic# = b.statistic#
4 and lower(a.name) in
5 ('redo size','undo change vector size');
NAME VALUE
---------------------------------------------------------------- ----------
redo size 602352
undo change vector size 82756
--redo
SQL> select 22000-780 "create redo size" from dual;
create redo size
----------------
21220
SQL> select 602352-22000 "insert redo size" from dual;
insert redo size
----------------
580352
--undo
SQL> select 6308-136 "create undo size" from dual;
create undo size
----------------
6172
SQL> select 82756-6308 "insert undo size" from dual;
insert undo size
----------------
76448
在这个试验中，create table产生redo:21220,undo:6172,insert into产生redo:580352,undo:76448;整个过程产生的redo:601572(
21220+580352),undo:82620(6172+76448)
8.CAST+NOLOGGING(TABLE)
SQL> alter system flush buffer_cache;
System altered.
Elapsed: 00:00:03.35
SQL> alter system flush shared_pool;
System altered.
Elapsed: 00:00:00.04
SQL>
SQL> select a.name, b.value
2 from v$statname a, v$mystat b
3 where a.statistic# = b.statistic#
4 and lower(a.name) in
5 ('redo size','undo change vector size');
NAME VALUE
---------------------------------------------------------------- ----------
redo size 732
undo change vector size 136
Elapsed: 00:00:00.05
SQL> create table chf.t_xifenfei_move_cast_N nologging tablespace users
2 as
3 select * from chf.t_xifenfei_move;
Table created.
Elapsed: 00:00:56.41
SQL> select a.name, b.value
2 from v$statname a, v$mystat b
3 where a.statistic# = b.statistic#
4 and lower(a.name) in
5 ('redo size','undo change vector size');
NAME VALUE
---------------------------------------------------------------- ----------
redo size 769848
undo change vector size 124944
SQL> select 769848-732 "redo size" from dual;
redo size
----------
769116
SQL> select 124944-136 "undo size" from dual;
undo size
----------
124808
这个试验产生的redo:769116,undo:124808
9.通过试验得出结论
1)sql hint中的nologgging无效
2)普通的cast(不含hint)，其本质是append，无nologgging
3)nologgging(表级别)可以使得cast效率较高
4)nologgging(表级别)+append(hint)可以使得insert效率较高
MOVE和CAST比较(续)
本篇文章是MOVE和CAST比较的续篇，主要是对于第一篇中没有涉及到的redo和undo的情况加以叙述
1.查询move产生redo和undo量
SQL> alter system flush buffer_cache;
System altered.
SQL> alter system flush shared_pool;
System altered.
SQL> select a.name, b.value
2 from v$statname a, v$mystat b
3 where a.statistic# = b.statistic#
4 and lower(a.name) in
5 ('redo size','undo change vector size');
NAME VALUE
---------------------------------------- ----------
redo size 844
undo change vector size 136
SQL> ALTER TABLE CHF.T_XIFENFEI_MOVE MOVE TABLESPACE TEST_OCP;
Table altered.
SQL> select a.name, b.value
2 from v$statname a, v$mystat b
3 where a.statistic# = b.statistic#
4 and lower(a.name) in
5 ('redo size','undo change vector size');
NAME VALUE
---------------------------------------- ----------
redo size 873074928
undo change vector size 110748
--产生redo
SQL> select 873074928-844 "redo size" from dual;
redo size
----------
873074084
--产生undo
SQL> select 110748-136 "undo size" from dual;
undo size
----------
110612
2.查询cast产生redo和undo 大小
SQL> alter system flush buffer_cache;
System altered.
SQL> alter system flush shared_pool;
System altered.
SQL> select a.name, b.value
2 from v$statname a, v$mystat b
3 where a.statistic# = b.statistic#
and lower(a.name) in
4 5 ('redo size','undo change vector size');
NAME VALUE
---------------------------------------------------------------- ----------
redo size 776
undo change vector size 136
SQL> create table chf.t_xifenfei_move_new tablespace users
2 as
3 select * from chf.t_xifenfei_move;
Table created.
SQL> select a.name, b.value
2 from v$statname a, v$mystat b
3 where a.statistic# = b.statistic#
4 and lower(a.name) in
5 ('redo size','undo change vector size');
NAME VALUE
---------------------------------------------------------------- ----------
redo size 873017580
undo change vector size 115340
--产生redo
SQL> select 873017580-776 "redo size" from dual;
redo size
----------
873016804
--产生undo
SQL> select 115340-136 "undo size" from dual;
undo size
----------
115204
3.两次实验比较
--redo(分母使用cast操作产生redo)
SQL> select 873074084-873016804 "redo" from dual;
redo
----------
57280
SQL> select 57280/873074084 from dual;
57280/873074084
---------------
.000065607
--undo(分母使用cast操作产生undo)
SQL> select 110612-115204 undo from dual;
undo
-------------
-4592
SQL> select 4592/115204 from dual;
4592/115204
-----------
.039859727
通过这两个的比较可以知道move操作产生的redo多了万分之七不到，undo少了百分之四，这些也是在实验允许的误差范围内，再说move操作还包括了cast的一些后续步骤在其中，所以通过这个验证和上一篇试验(MOVE和CAST比较)，基本上可以大胆操作move操作的本质就是全表扫描+append插入数据，操作过程中产生的redo大小几乎和表本身大小(872415232)相等,这个证明,move和cast都是以logging模式运行(数据库本身是非force logging模式)
MOVE和CAST比较
1.创建模拟表
SQL> select * from v$version;
BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
PL/SQL Release 11.2.0.3.0 - Production
CORE 11.2.0.3.0 Production
TNS for Linux: Version 11.2.0.3.0 - Production
NLSRTL Version 11.2.0.3.0 - Production
SQL> create table chf.t_xifenfei_move
2 as
3 select * from dba_objects;
Table created.
SQL> select count(*) from chf.t_xifenfei_move;
COUNT(*)
----------
73585
SQL> create table chf.t_xifenfei_move
2 as
3 select * from dba_objects;
Table created.
SQL> select count(*) from chf.t_xifenfei_move;
COUNT(*)
----------
73585
SQL> DECLARE
2 i NUMBER;
3 BEGIN
4 FOR i IN 1..100 LOOP
5 INSERT INTO chf.t_xifenfei_move
6 select * from dba_objects;
7 END LOOP;
8 COMMIT;
9 END;
10 /
PL/SQL procedure successfully completed.
SQL> exec dbms_stats.gather_table_stats('CHF','T_XIFENFEI_MOVE');
PL/SQL procedure successfully completed.
SQL> select bytes from dba_segments where segment_name='T_XIFENFEI_MOVE';
BYTES
----------
872415232
2.测试move
2.1)执行move操作，记录时间
SQL> alter system flush buffer_cache; System altered. SQL> SET TIMING ON; SQL> alter session set events 2 '10046 trace name context forever,level 1'; Session altered. Elapsed: 00:00:00.00 SQL> ALTER TABLE CHF.T_XIFENFEI_MOVE MOVE TABLESPACE USERS; Table altered. Elapsed: 00:02:11.77 SQL> alter session set events 2 '10046 trace name context off'; Session altered. Elapsed: 00:00:00.04 SQL> select d.value||'/'||lower(rtrim(i.instance,chr(0)))||'_ora_'||p.spid||'.trc' trace_file_name from 2 (select p.spid from v$mystat m, v$session s,v$process p where m.statistic# = 1 and s.sid = m.sid and p.addr = s.paddr ) p, 3 (select t.instance from v$thread t,v$parameter v where v.name = 'thread' and(v.value = 0 or t.thread# = to_number(v.value))) i, 4 (select value from v$parameter where name = 'user_dump_dest') d; TRACE_FILE_NAME -------------------------------------------------------------------------------- /opt/oracle/diag/rdbms/chf/chf/trace/chf_ora_4765.trc
从这里可以看出，move操作执行了00:02:11.77
2.2)查看trace内容
[oracle@node1 ~]$ tkprof /opt/oracle/diag/rdbms/chf/chf/trace/chf_ora_4765.trc /tmp/xifenfei_move.txt
TKPROF: Release 11.2.0.3.0 - Development on Tue Jan 10 10:57:59 2012
Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.
********************************************************************************
SQL ID: c1yk5pv0v1wg1 Plan Hash: 2931676921
ALTER TABLE CHF.T_XIFENFEI_MOVE MOVE TABLESPACE USERS
call count cpu elapsed disk query current rows
------- ------ -------- ---------- ---------- ---------- ---------- ----------
Parse 1 0.00 0.05 7 8 0 0
Execute 1 11.29 131.23 105584 106275 115654 7432085
Fetch 0 0.00 0.00 0 0 0 0
------- ------ -------- ---------- ---------- ---------- ---------- ----------
total 2 11.30 131.29 105591 106283 115654 7432085
Misses in library cache during parse: 1
Optimizer mode: ALL_ROWS
Parsing user id: SYS
Number of plan statistics captured: 1
Rows (1st) Rows (avg) Rows (max) Row Source Operation
---------- ---------- ---------- ---------------------------------------------------
0 0 0 LOAD AS SELECT (cr=117799 pr=105602 pw=105585 time=131351005 us)
7432085 7432085 7432085 TABLE ACCESS FULL T_XIFENFEI_MOVE (cr=105591 pr=105586 pw=0 time=4735560 us cost=23453 size=720912245 card=7432085)
********************************************************************************
从这里可以看出执行move，其实本质是全表扫描表，然后append方式插入数据，而不是真的数据块拷贝
3.测试CAST
3.1).CAST插入数据过程
SQL> alter system flush buffer_cache;
System altered.
SQL> SET TIMING ON;
SQL> alter session set events
2 ‘10046 trace name context forever,level 1’;
Session altered.
Elapsed: 00:00:00.01
SQL> create table chf.t_xifenfei_move_new tablespace test_ocp
2 as
3 select * from chf.t_xifenfei_move;
Table created.
Elapsed: 00:01:59.22
SQL> alter session set events
2 ‘10046 trace name context off’;
Session altered.
Elapsed: 00:00:00.00
SQL> select d.value||’/’||lower(rtrim(i.instance,chr(0)))||’_ora_’||p.spid||’.trc’ trace_file_name from
2 (select p.spid from v$mystat m, v$session s,v$process p where m.statistic# = 1 and s.sid = m.sid and p.addr = s.paddr ) p,
3 (select t.instance from v$thread t,v$parameter v where v.name = ‘thread’ and(v.value = 0 or t.thread# = to_number(v.value))) i,
4 (select value from v$parameter where name = ‘user_dump_dest’) d;
TRACE_FILE_NAME
——————————————————————————–
/opt/oracle/diag/rdbms/chf/chf/trace/chf_ora_5121.trc
从这里看出cast操作用时:00:01:59.22，比move稍微少，但是cast要实现move完全的功能，还需要表重命名，表授权，编译无效对象等。
3.2)查看trace内容
[oracle@node1 ~]$ tkprof /opt/oracle/diag/rdbms/chf/chf/trace/chf_ora_5121.trc /tmp/xifenfei_create.txt
TKPROF: Release 11.2.0.3.0 - Development on Tue Jan 10 11:08:19 2012
Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.
********************************************************************************
create table chf.t_xifenfei_move_new tablespace test_ocp
as
select * from chf.t_xifenfei_move
call count cpu elapsed disk query current rows
------- ------ -------- ---------- ---------- ---------- ---------- ----------
Parse 1 0.00 0.02 1 4 0 0
Execute 1 9.85 118.37 105587 106097 112387 7432085
Fetch 0 0.00 0.00 0 0 0 0
------- ------ -------- ---------- ---------- ---------- ---------- ----------
total 2 9.85 118.40 105588 106101 112387 7432085
Misses in library cache during parse: 1
Optimizer mode: ALL_ROWS
Parsing user id: SYS
Number of plan statistics captured: 1
Rows (1st) Rows (avg) Rows (max) Row Source Operation
---------- ---------- ---------- ---------------------------------------------------
0 0 0 LOAD AS SELECT (cr=106631 pr=105592 pw=105585 time=118338607 us)
7432085 7432085 7432085 TABLE ACCESS FULL T_XIFENFEI_MOVE (cr=105591 pr=105586 pw=0 time=2935008 us cost=23453 size=720912245 card=7432085)
********************************************************************************
通过这个可以看出，CAST其实本质也是全表扫描，然后append方式插入数据
4.比较move和cast
4.1)通过比较执行时间，cast稍微少，但是还有后续操作需要时间
4.2)通过比较执行计划，两者是一样的
4.3)move操作在整个过程中都会锁表,而cast不会锁住原表(select+where可以减少停业务时间)
4.4)move操作会一次性处理好权限,plsql/view等有效,而cast在rename之后，相关对象可能需要重新编译，重新授权等操作
4.5)cast操作index需要新建(create),而move操作index需要重建(rebuild)
4.6)cast完成后，需要对表重命名，删除原表操作操作，而这个操作move不用
5.选择使用谁
5.1)如果停业务时间够长，建议使用move操作
5.2)如果停业务时间不能太长，可以使用cast+where实现
5.3)如果数据库版本>=10g,且表空间使用local管理，那么可以考虑在不停业务的情况下使用shrink实现类此功能
至于MOVE和CAST在执行过程中，关于产生的redo和undo的比较，请见下篇:MOVE和CAST比较(续)
