Oracle 12c new feature:OFFSET n FETCH n row-limit

在分页查询或top n中在oracle 之间的版本使用rownum,row_number..,从12c 提供了offset fetch 的语法,其实这个语法不是什么新鲜玩意,在DB2,MSSQL,MYSQL,PostgreSQL之前也都提供的语法。

oracle 12c new feature: moving online datafiles(在线移动数据文件)

在12c以前如果想移动表空间的数据文件首先要offline.再OS mv命令移动离线的数据文件到新路径,Recover datafile[ or tablespace or database] 再Online.从12c 开始可以移动Online 的数据文件了。

案例:latch: cache buffers chains event tuning

前两天对oracle数据库(single instance)进行了迁移升级从10.2.0.4 升到11.2.0.3,有一个项目迁完后第二天,cpu负载升到了130更高(16cpus). 向用户询问后使用上没有改变,平时就几个人使用,而该用户活动会话就有100多个。最在等待CBC latch. 怀疑是执行计划发生了改变。

oracle 12c Database Architecture (CDB、PDB)

Database Architecture consists of
1) Container Database (CDB)
2) Pluggable Database (PDB)

Script: RMAN backup shell on linux

# make direcory for backset file and scripts file,in my […]


Expdp Exclude schemas or tables while full=y(排除指定schema的全备份)

当做EXPDP 逻辑备份时常用到FULL=Y 的全库备份,但是有些schema不想每次都备份如一些自带的schemas(如APEX_030200),这时可以使用exclude很方便的排除…


About redo log wait events

log file sync wait 默认是发生在前台进程发进commits时比如用户commit,DDL,递归操作发生在dictionary table 上的DML,同时rollback 也会导致…

How to hanganalyze and systemstate dumps

Oracle support request hang analysis and system state d […]

How to Encrypt Your Bash Shell Script on Linux Using SHC?(加密shell script)

当需要写shell连接数据库取一些数据或备份等操作时,shell中可能包含数据库的用户密码等敏感信息,被一些不怀好意的人发现是你的灾难,出于安全的考虑需要对shell明文加密,使用shc 就可以把原shell编译为可执行程序(二进制),这样就无法再明文打开shell。

Manually create physical standby DG ,Switchover, Convert to Logical standby(Scripts and Short Descriptions)

Manually create physical standby with rman;
Primary role and Primary standby role switchover;
Converting Physical Standby to Logical Standby ;


CTAS will loss default value define on columns

The CTAS operation although copies column constraints such as NULL, NOT NULL from the normal table to the partitioned table during the partitioned table creation, it does not copy DEFAULT VALUEs of the columns.

script:purge ADR file

[oracle@db231 ~]$ ./adr_purge
INFO: Purge started at Thu May 16 07:35:32 CST 2013
INFO: adrci purge started at Thu May 16 07:35:32 CST 2013
INFO: adrci purging diagnostic destination diag/tnslsnr/db231/listener
INFO: purging ALERT older than 90 days …
INFO: purging INCIDENT older than 30 days …

ORA-12034: materialized view log on xx.xx younger than last refresh when a mview fast refresh after Impdp

ORA-12012: error on auto execute of job 88
ORA-12034: materialized view log on “TOPBOX”.”TOPBOX_COURSESTUDY” younger than last refresh
ORA-06512: at “SYS.DBMS_SNAPSHOT”, line 2256


Tuning “Backup:sbtbackup” Event

A few days ago a friend ask me to see a awr issue. In t […]


因一次硬件原因导致了服务器异常停机,防止蝴蝶效应及时进行了数据迁移,一周发现了这个决定正确的。 申请了2小时的 […]

About ORACLE CPU, PSU, SPU Patch Nomenclature

It all started in January 2005 with Critical Patch Updates (CPU). Then Patch Set Updates (PSU) were added as cumulative patches that included priority fixes as well as security fixes.

Backup ASM metadata with shell

Creates a backup directory if required, works out the A […]

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linux发送手机短信 利用fesion robot



Tuning “Read by other session wait” Event

This wait event occurs when we are trying to access a buffer in the buffer cache but we find that the buffer is currently being read from disk by another user so we need to wait for that to complete before we can access it.


客户要求导出大量的数据(约800万记录),开始为了格式上的好看生成的是ACCESS数据库文件,用Toad 11 […]