看到一篇不错的文章 转载下
Nuno Souto (Noons) also asked a really interesting question on my Differences between Unique and Non-Unique Indexes blog entry (comment 4) that I thought it worthy of a separate blog entry to do the answer justice. The question was:
“Isn’t it still the case that unique indexe[……]
December 27, 2011 oracle, replication No comments Stream
测试环境：
[oracle@liu ~]$ sqlplus ‘/as sysdba’
SQL*Plus: Release 10.2.0.1.0 – Production on Mon Dec 26 21:53:23 2011
Copyright (c) 1982, 2005, Oracle. All rights reserved.
Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 – Production
With the Partitioning, OLAP an[……]
December 23, 2011 oracle, replication No comments dataguard
总结下今天DG碰到的问题，本来一个很简单的问题，被我们复杂化衍生出很多问题。
Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 – 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> show parameter check
NAME TYPE VALUE
——————————[……]
December 22, 2011 maintain, oracle No comments structure
结构如下图所示：
对于分支节点块（包括根节点块）来说，其所包含的索引条目都是按照顺序排列的（缺省是升序排列，也可以在创建索引时指定为降序排列）。每个索引条目（也可以叫做每条记录）都具有两个字段。第一个字段表示当前该分支节点块下面所链接的索引块中所包含的最小键值；第二个字段为四个字节，表示所链接的索引块的地址，该地址指向下面一个索引块。在一个分支节点块中所能容纳的记录行数由数据块大小以及索引键值的长度决定。比如从上图一可以看到，对于根节点块来说，包含三条记录，分别为（0 B1）、（500 B2）、（1000 B3），它们指向三个分支节点块。其中的0、500和1000分别表示这三个分支节[……]
December 20, 2011 maintain, oracle No comments LOB
16号早上10点左右发现系统变慢，查看等待事件 发现大量i/o salve wait, load 比值增加，等待语句sql_id为 38wm92jbxu0vf
09:59:30 up 80 days, 8:00, 2 users, load average: 16.02, 4.67, 2.95
SID USERNAME MACHINE EVENT SQL ST LT LOGON_TIME
—— ——–[……]
December 19, 2011 maintain, oracle No comments hint
Limitations of DRIVING_SITE Hint
Applies to:
Oracle Server – Enterprise Edition – Version: 9.2.0.1 to 11.2.0.2
This problem can occur on any platform.
Symptoms
For optimization of distributed queries Oracle provides the DRIVING_SITE hint.
The Oracle? Database Administrator’s G[……]
December 18, 2011 11g, oracle, RAC No comments upgrade
基于windows 2008平台升级rac 11.2.0.2.0->11.2.0.3.0
OS环境windows 2008 x64 数据库环境oracle 11g rac ,version 11.2.0.2.0 64bit
SQL> conn / as sysdba
已连接。
SQL> select * from v$version;
BANNER
——————————————————————————–
Oracle Database 11g Enterpris[……]
December 17, 2011 Internals, oracle No comments scripts
该script 显示各个cursor占用的heap大小
——————————————————————————–
—
— File name: curheaps.sql
— Purpose: Show main cursor data block heap sizes and their contents
— (heap0 and heap6)
—
— Author: Tanel Poder
— C[……]
December 16, 2011 11g, backup, oracle No comments 11g
11g Release 2 RMAN Backup Compression
Oracle 11g Release 2 introduced compression algorithm levels which can be used for compressing table data, Data Pump exports and RMAN backups as well.
The compression levels are BASIC, LOW, MEDIUM and HIGH and each affords a trade off related to backup throu[……]
December 16, 2011 oracle, replication No comments dataguard
今天新上线的系统物理备库出现以下错误：
[oracle@db-15 ~]$ sqlplus ‘/as sysdba’
SQL*Plus: Release 10.2.0.5.0 – Production on Fri Dec 16 20:37:38 2011
Copyright (c) 1982, 2010, Oracle. All Rights Reserved.
Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 – 64bit Production
With t[……]