VMCD.ORG

Physical-standby standbylogfile checksum error

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
——————————[……]

BTREE索引浅解

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[……]

一次LOB字段的查询导致的系统问题以及sql_id变化的探究

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
—— ——–[……]

Limitations of DRIVING_SITE Hint

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[……]

快速升级Oracle 11.2.0.2 RAC到11.2.0.3 on Windows 2008

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[……]

Scripts:curheaps.sql

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[……]

[转] 11g Release 2 RMAN Backup Compression

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[……]