ITPub博客

重做日志文件和重做日志组的状态[@more@]一、日志文件的状态包括：1、NULL -File is in use2、STALE-contents of the file are incomplete3、INVALID-File is inaccessible4、DELETED-File is no longer used二、重做日志组的状态包括：1、CURRENT-Current redo log.This implies that the redo log is active.The redo log could be open or closed.2、UNUSED-Online redo log has never been written to.This is the status of a redo log that was just added.or just after a RESETLOGS.when it is not the current redo log3、ACTIVE

记录几个视图的用处[@more@]1、V$SYSSTAT The view contains instance-wide information regarding rollback segment,datafile I/O,parse data,and so on.To locate information regareding memory-related problems in the database, you can use this view.2、V$SGAThe view only contain information regarding the distribution of SGA memory into different SGA components.3、V$SESSIONThe view displays session-specific information4、V$ROLLSTATThe view contains information specific to rollback segments5、V$FILESTATThe

以前总有一个疑问，在什么情况下，才会出现，还没有commit，就已经将数据从data buffer写到数据文件上的情况？顺道记一下checkpoint产生的情况。[@more@]1、在commit前有cheakpoint发生2、data buffer 不够用时暂时想到这么多。checkpoint会刷新脏数据，但什么时候会发生checkpoint呢？以下几种情况会触发checkpoint。1.当发生日志组切换的时候2.当符合LOG_CHECKPOINT_TIMEOUT，LOG_CHECKPOINT_INTERVAL，FAST_START_IO_TARGETFAST_START_MTTR_TARGET参数设置的时候*13.当运行ALTER SYSTEM SWITCH LOGFILE的时候4.当运行ALTER SYSTEM CHEC

oracle中经常会考到的几个状态，invalid,obsolete,expired,stale等等。自己试着总结一下[@more@]1、If one of the online redo log members is lost,the status in v$logfie will be INVALID 2、If the contents of the redo log file are incomplete ,the status of the file in the V$LOGFILE view will be STALE3、You are using RMAN to perform backup and recovery on your database.The backup of one of the files was lost because it was located on a failed media.If you use CROSSCHECK command to verify the existence of

似乎有一个oracle 原厂培训的机会...[@more@]昨天还和阿春谈起，想考oracle的OCP认证，需要一门oracle原厂培训。今天，机会就来了。本来是要给阿春去的，不过阿春又一个oracle adminstrator 1的培训了，他把这个培训让给我了。不知道领导会不会安排我去，如果能搞定这次培训，OCP就不是问题了。

RMAN是不备份online redo log的。这个问题一直比较困惑，难道online redo log不需要备份？确实是的[@more@]看下面这段Avoiding the Backup of Online Redo LogsAlthough it may seem that you should back up online redo logs along with the datafiles and control file, this technique is dangerous. You should not back up online redo logs for the following reasons:* The best method for protecting the online logs against media failure is by multiplexing them, that is, having multiple log members in each group, on

Optimizer statistics are a collection of data that describe more details about the database and the objects in the database. These statistics are used by the query optimizer to choose the best execution plan for each SQL statement. [@more@] Optimizer statistics include the following:Table statisticsNumber of rowsNumber of blocksAverage row lengthColumn statisticsNumber of distinct values (NDV) in columnNumber of nulls in columnData distribution (histogram)Index statisticsNumber of leaf blocksLev

The NLS_LANG environment variable specifies the language,territory,and charater set support by the user session in an oracle 10g database.[@more@]The format to specify NLS_LANG is _..The portion specifies the default data format,numeric format,and monetary formats.The default data format assigned to the Oracle 10g database will be DD-MON-YY.

while installing the Oracle 10g database on a UNIX platform,you are prompted to run the scirpt file orainstRoot.sh ,which creates another file orainst.loc[@more@].oraInst.loc file is used to find the inventory location when Oracle Universal Installer startup.It is not used by Oracle Universal Installer to store the home directory and base directory locations.No particular file stores the home directory and base directory.These are specified by environment variables.

To shrink table and its dependant segments,you should use the ALTER TABLE ** SHRINK SPACE CASCADE;statement .Using the CASCADE clause shrinks all the dependant segments of the ** table to release the unused space below and above the High Water Mark(HWM).[@more@]The table should be located in a tablespace on which automatic segment space management is enabled.If the table is loacted in a tablespace on which manual segment space management is enabled,you cannot shrink the table.

TIMESTAMP WITH TIME ZONE和TIMESTAMP WITH LOCAL TIME ZONE的实践理解.TIMESTAMP WITH LOCAL TIME ZONE会随着用户所在时区(SESSIONTIMEZONE)而变化，而TIMESTAMP WITH TIME ZONE则不随用户所在时区的变化而变，简单的说，这两个时间类型的参照时间不同，一个是参照用户的时区，一个是参照数据库的时区。[@more@]实践过程：1.建实践用表：SQL> DROP TABLE TIMESTAMP_TEST;表已删除。SQL> CREATE TABLE TIMESTAMP_TEST(2 TIME DATE,3 TIMESTP TIMESTAMP(3),4 TIMESTP_TZ TIMESTAMP(3) WITH TIME ZONE,5 TIMESTP_LTZ TIMESTAMP(3) WIT

和张主任的谈话[@more@]今天张主任问我关于东二广播故障的问题，我对问题描述不是很清晰，感觉张主任似乎不是很满意，唉，没有给他一个好印象，不知道将来去开发部的事情会如何了。发现自己描述问题的能力真的很差，思路不是很清晰，什么都想说给别人听，没有把握住重点。8月2号还要和他去开会，顺道聊聊看吧。

客户端连接oracle数据库，需要配置的文件包括，sqlnet.ora和tnsname.ora.tnsname.ora就是起一个“数据库网络服务名”解析的功能[@more@]先来一个tnsnames.ora文件的样板：test=(DEscriptON=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=testserver)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=orcl.testserver.com)))现解释如下：test：为网络服务名（net service name），也叫数据库别名。SERVICE_NAME:该参数是 Oracle8i 新引进的。在8i以前，我们用 SID 来表示标识数据库的一个实例，但是在 Oracle 的并行环境中，一个数据库对应多个实例

密码重用规则涉及的2个参数,password_login_max和password_login_time.这2个参数的设置及其规则与oracle9i是不同的.[@more@]PASSWORD_REUSE_TIME是重用密码的最小时间间隔，单位是天。可以给出整数或分数，如1/1440表示1分钟（出于效率的考虑，oracle不会每分钟都去进行检查，一般来说，有5分钟左右的误差，因此如果这个数小于1/144则没有多大的意义）。PASSWORD_REUSE_MAX是重用密码前更换密码的最小次数。这两项本身没有任何异议，关键是两项如何配合使用。可以分为3种情况进行描述：一、两项都设为unlimited，这是profile的default设置

开心的晚餐[@more@]晚上打球回来,洗个澡,坐下来吹吹空调,舒服的很.自己不怎么会打羽毛球,纯粹是为了出一身汗,运动运动.打球的过程也相当搞笑,笑得我肚子疼.晚上和她一起出去吃饭,聊得很开心,虽然我一直都知道,我们是不可能的,但是我还是希望能陪在她的身边.真不知道自己何时才能放开.反正自己现在也没有心情找gf,权当做一个聊得来的异性朋友吧.和她打了个赌,输了的请客去泡温泉.输赢我不在意,输了我也很开心,其实就是找个理由约她出去玩玩.不过,话说回来,我还是很有把握能赢的,嘿嘿~~~~~^_^吃晚饭送她回去,到了十字路口,我突然决定不坐公车

lsnrctl> reload L1 dynamiclly reset the lisner,L1, with the new settings and rules defined in listener.ora file.[@more@]lsnrctl> reload L1 dynamiclly reset the lisner,L1, with the new settings and rules defined in listener.ora file.This command don't stop listener L1.The new setting are applied dynamically.The command dont reset all client connections.The settings are applied dynamically without modifying the current sessions.

The parameter trace_level_listener is set in listener.ora file and setting this parameter to a value of 16 provides maximum trace information for troubleshooting information for Oracle Support service.[@more@]The parameter is in the listener.ora file specifies the level of detail that will be captured in listener trace records.This parameter can be set a value between 0 and 16,where a zero value indicates no listeners tracing and a value of 16 indicates maximum tracing of listeners .This paramet

by session对每个session中发生的重复操作只记录一次by access对每个session中发生的每次操作都记录，而不管是否重复都记录数据库初始化参数文件中AUDIT_TRAIL＝OS时，审计记录存在操作系统的文件中，AUDIT_TRAIL＝DB时，审计记录存在数据库中。[@more@]作为DBA应该知道有那些用户或那些操作是影响数据库安全性，要知道这些起码要查看某一段时间数据库的所有操作，然后分析这些操作有那些是有隐患的、危险的，要达到这个目的必须应用数据库审计功能....................数据库审计可以记录对数据库对象的所有操作，什么时候、什么用户对什

准备oracle10g的oca考试,写一点自己的学习心得,还有那些总记不住地东西,希望对自己的学习有帮助,从今天开始,努力ing...[@more@]