rac中的spfile探讨

发表于 2011 年 10 月 10 日 由 惜分飞

今天朋友的的rac，因为被同事做数据库升级，分别在两个节点的本地创建了spfile，然后使用这个spfile启动了数据库，因为他不是非常懂oracle，所以向我求救，我改他的建议是：
1、利用备份的原来的pfile文件创建在asm中的spfile，规则是：+ASM/SID/spfileSID
2、dbs目录下创建一个本地的initsid.ora，然后在里面加一个spfile=’+ASM pfile path’（两个节点同样操作，注意sid不同）
3、分别重启数据库
出现该问题的原因分析：
做数据库升级的朋友的同事也不懂rac的spfile的相关规则，应该是在重启数据库的时候，提示spfile不存在，然后自己手工创建利用pfile创建的spfile到dbs下面，然后朋友十一后检测数据库，发现spfile都放置在本地了。

1、通常读取参数文件顺序
我们知道，如果不指定参数文件，oracle是按照这个顺序查找文件来启动数据库的：
spfileSID.ora
spfile.ora
initSID.ora
init.ora
如果这些文件都没有找到，启动会失败。

2、RAC中关于spfile的启动探讨

[rac@cent1 dbs]$ echo $ORACLE_SID
RACDB1
[rac@cent1 dbs]$ touch spfileRACDB1.ora  <==手工创建一个空白的spfile
[rac@cent1 dbs]$ sqlplus / as sysdba

SQL*Plus: Release 10.2.0.4.0 - Production on Thu Apr 29 13:45:50 2010

Copyright (c) 1982, 2007, Oracle.  All Rights Reserved.

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - Production
With the Partitioning, Real Application Clusters, OLAP, Data Mining
and Real Application Testing options

SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORA-27091: unable to queue I/O  <== 用sqlplus启动数据库时会报错
ORA-27069: attempt to do I/O beyond the range of the file
Additional information: 1
Additional information: 1
SQL>
SQL> exit
Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - Production
With the Partitioning, Real Application Clusters, OLAP, Data Mining
and Real Application Testing options
[rac@cent1 dbs]$ crs_stat -t
Name           Type           Target    State     Host
------------------------------------------------------------
ora....B1.inst application    OFFLINE   OFFLINE
ora....B2.inst application    ONLINE    ONLINE    cent2
ora.RACDB.db   application    ONLINE    ONLINE    cent1
ora....SM1.asm application    ONLINE    ONLINE    cent1
ora....T1.lsnr application    ONLINE    ONLINE    cent1
ora.cent1.gsd  application    ONLINE    ONLINE    cent1
ora.cent1.ons  application    ONLINE    ONLINE    cent1
ora.cent1.vip  application    ONLINE    ONLINE    cent1
ora....SM2.asm application    ONLINE    ONLINE    cent2
ora....T2.lsnr application    ONLINE    ONLINE    cent2
ora.cent2.gsd  application    ONLINE    ONLINE    cent2
ora.cent2.ons  application    ONLINE    ONLINE    cent2
ora.cent2.vip  application    ONLINE    ONLINE    cent2
[rac@cent1 dbs]$ srvctl start instance -i racdb1 -d racdb  <== 用srvctl启动成功
[rac@cent1 dbs]$ sqlplus / as sysdba

SQL*Plus: Release 10.2.0.4.0 - Production on Thu Apr 29 13:47:25 2010

Copyright (c) 1982, 2007, Oracle.  All Rights Reserved.

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - Production
With the Partitioning, Real Application Clusters, OLAP, Data Mining
and Real Application Testing options

SQL> select instance_name, status from v$instance;

INSTANCE_NAME    STATUS
---------------- ------------
RACDB1           OPEN
--说明srvctl不是用那个顺序去查找参数文件

3、查看srvctl读取spfile位置

[rac@cent1 dbs]$ srvctl config database -d racdb -a
cent1 RACDB1 /rac/product/10.2.0/db
cent2 RACDB2 /rac/product/10.2.0/db
DB_NAME: RACDB
ORACLE_HOME: /rac/product/10.2.0/db
SPFILE: +DATA/RACDB/spfileRACDB.ora
DOMAIN: WORLD
DB_ROLE: null
START_OPTIONS: null
POLICY:  AUTOMATIC
ENABLE FLAG: DB ENABLED

4、修改CRS中关于spfile位置

[rac@cent1 dbs]$ srvctl modify database -d racdb -p ' +DATA/RACDB/spfileRACDB1.ora'
发表在 Oracle RAC | 一条评论

利用rowid排序更新大表数据

发表于 2011 年 10 月 10 日 由 惜分飞

现在有个案例，有一张很大的表t1，需要更新其中的一个列，然后这个列是参考另外一个表t2中的列
直接sql操作如：
update t1 ta set prov_code=(select area_code from t2 tb where ta.id=tb.id);

利用rowid，分批提交的思路写出如下sql，执行大表更新效率比较高

DECLARE
  CURSOR cur IS
    SELECT
     a.area_code, b.ROWID ROW_ID
      FROM t2 a, t1 b
     WHERE a.id = b.id
     ORDER BY b.ROWID;  
  V_COUNTER NUMBER;
BEGIN
  V_COUNTER := 0;
  FOR row IN cur LOOP
    UPDATE t1
       SET prov_code = row.area_code
     WHERE ROWID = row.ROW_ID;
    V_COUNTER := V_COUNTER + 1;
    IF (V_COUNTER >= 1000) THEN
      COMMIT;
      V_COUNTER := 0;
    END IF;
  END LOOP;
  COMMIT;
END;

这里利用了rowid排序，使得update操作是一个一个数据块的进行，减少逻辑读，分批提交减小undo压力

发表在 Oracle 开发 | 一条评论

Startup Migrate

发表于 2011 年 10 月 9 日 由 惜分飞

1、为什么要使用Startup Migrate
STARTUP MIGRATE was introduced in 9.2 as a mechanism to be sure that most everything that needs to be done to run an upgrade script or a patch script is done automatically. In the past, customers were expected to adjust certain initialization parameters prior to beginning an upgrade or applying a a patch, but most of this is now done automatically by STARTUP MIGRATE. When a customer starts a database in MIGRATE mode, the following ALTER SYSTEM commands will be set automatically:
ALTER SYSTEM ENABLE RESTRICTED SESSION;
ALTER SYSTEM SET “_SYSTEM_TRIG_ENABLED”=FALSE SCOPE=MEMORY;
ALTER SYSTEM SET _undo_autotune=FALSE SCOPE=MEMORY;
ALTER SYSTEM SET undo_retention=900 SCOPE=MEMORY;
ALTER SYSTEM SET JOB_QUEUE_PROCESSES=0 SCOPE=MEMORY;
ALTER SYSTEM SET AQ_TM_PROCESSES=0 SCOPE=MEMORY;
这些我们可以从数据库的Startup Migrate命令启动数据库的日志中可以看出来

Sun Oct  9 21:53:04 2011
ALTER SYSTEM enable restricted session;
Sun Oct  9 21:53:04 2011
ALTER SYSTEM SET _system_trig_enabled=FALSE SCOPE=MEMORY;
Autotune of undo retention is turned off. 
Sun Oct  9 21:53:04 2011
ALTER SYSTEM SET _undo_autotune=FALSE SCOPE=MEMORY;
Sun Oct  9 21:53:04 2011
ALTER SYSTEM SET undo_retention=900 SCOPE=MEMORY;
MMNL started with pid=12, OS id=8452
Sun Oct  9 21:53:04 2011
ALTER SYSTEM SET aq_tm_processes=0 SCOPE=MEMORY;
Sun Oct  9 21:53:04 2011
Resource Manager disabled during database migration: plan '' not set
Sun Oct  9 21:53:04 2011
ALTER SYSTEM SET resource_manager_plan='' SCOPE=MEMORY;
replication_dependency_tracking turned off (no async multimaster replication found)
Completed: ALTER DATABASE OPEN MIGRATE

2、Startup Migrate主用作用
在9i，无论升级/降级 数据库都是startup migrate
10g后增加了upgrade参数，升级可直接用startup upgrade，降级仍是startup migrate

3、Startup Migrate辅助作用（解决部分ORA-00701）

SQL> alter index I_H_OBJ#_COL# rebuild;
alter index I_H_OBJ#_COL# rebuild
*
ERROR at line 1:
ORA-00701: object necessary for warmstarting database cannot be altered

SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup migrate;
ORACLE instance started.
Total System Global Area 139531744 bytes
Fixed Size 452064 bytes
Variable Size 121634816 bytes
Database Buffers 16777216 bytes
Redo Buffers 667648 bytes
Database mounted.
Database opened.
SQL> alter index I_H_OBJ#_COL# rebuild;

Index altered.

SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORACLE instance started.

Total System Global Area 139531744 bytes
Fixed Size 452064 bytes
Variable Size 121634816 bytes
Database Buffers 16777216 bytes
Redo Buffers 667648 bytes
Database mounted.
Database opened.
发表在 Oracle | 评论关闭