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避免锁[@more@]

bigfile tablespace是Oracle10g的新特性。Bigfile tablespaces包含1个最大4G个blocks 的datafile。因此，使用8KBdata blocks 的bigfile tablespace 最大可以达到32TB。Bigfile tablespaces 常用于非常大的DB。 如果很大的DB有成千的 read/write datafiles, 那么checkpoints之类的操作将非常费时。如果用一个很大的datafile，减少datafiles的数量，将会提高效率。创建时使用BIGFILE关键字如下：CREATE BIGFILE TABLESPACE BIG_DEMODATAFILE '/ORADATA/PROD/BIG_DEMO.DBF' SIZE 25G;Smallfile tablespace是原Oracle tablesp

recover database using backup controlfile;1 指定日志: {<RET>=suggested | filename | AUTO | CANCEL}auto2 指定日志: {<RET>=suggested | filename | AUTO | CANCEL} cancel或者：2 指定日志: {<RET>=suggested | filename | AUTO | CANCEL}D:oracleproduct10.2.0oradatatestREDO01.LOG --filenamefilenameSQL> select status,group# from v$log;STATUS GROUP#---------------- ----------CURRENT 1INACTIVE 3INACTIVE 2[@more@]

为一个RAC搭建standby和单节点搭建方法基本一致，我们可以把RAC看成是一个单节点的数据库，只需要保证所有节点的日志能传送到备库即可。 一、在备库服务器安装ORACLE软件 只安装软件，不要创建数据库。ORACLE软件版本和主库保持一致。 二、修改主库参数 节点1执行： SQL> show parameter spfile NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ spfile string /dev/raw/raw14 节点2执行： SQL> show parameter spfile NAME TYPE VALUE ------------------

Large SGA On Linux On 32-bit Linux the total SGA size is limited to around 2Gig. There are several ways to allocate more memory than this, but the most robust and scalable method requires the use of a shared memory file, like shmfs in RHEL 2.1 or ramfs in RHEL 3-5. This article presents the methods necessary to create very large buffer caches on Red Hat Enterprise Linux and its clones. Red Hat Enterprise Linux (RHEL) 2.1 Create a shared memory file system (shmfs)Enabling big

BITMAP CONVERSION TO ROWIDS--------------------------------------------------------------------------------| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |-------------------------------------------------------------------------------------------------------------------| 0 | SELECT STATEMENT | | 16 | 944 | 139 (3)| 00:00:02 | | 1 | SORT GROUP BY | | 16 | 944 | 139 (3)| 00:00:02 | | 2 | NESTED LOOPS | | 16 | 944 | 138 (2)| 00:00:02 | | 3 | NESTED LOOPS | | 16 | 528 | 135 (3)| 00:00:02

Level 0 级是各增量备份的基础，那level 1 与level 2有什么不同呢？ 分两种情况，incremental的和cumulitive的，前者备份跟自己同级或比自己级别低的，后者只备份比自己级别低的 前者：level1备份上一次level1或level0以来的变化，level2备份上一次level2或level1或level0以来的变化 后者：level1备份上一次level0以来的变化，level2备份上一次level1或level0以来的变化[@more@]

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Table of Contents Rac11gR2OnLinux............................................................................................................................................1 1. Introduction........................................................................................................................................1 1.1. Overview of new concepts in 11gR2 Grid Infrastructure...................................................1 1.1.1. SCAN..................................................

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oracle 实现按周,月,季度,年查询统计数据 //按自然周统计 select to_char(date,'iw'),sum() from where group by to_char(date,'iw') //按自然月统计 select to_char(date,'mm'),sum() from where group by to_char(date,'mm') //按季统计 select to_char(date,'q'),sum() from where group by to_char(date,'q') //按年统计 select to_char(date,'yyyy'),sum() from where group by to_char(date,'yyyy') Oracle 中 IW和WW 有何差别 SQL> select day, 2 to_cha

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Solution -- Create new undo tablespace with smaller size.SQL> create undo tablespace UNDO_RBS1 datafile 'undorbs1.dbf' size 100m;-- Set new tablespace as undo_tablespaceSQL> alter system set undo_tablespace=undo_rbs1;-- Drop the old tablespace.SQL> drop tablespace undo_rbs0 including contents.NOTE: Dropping the old tablespace may give ORA-30013 : undo tablespace '%s' is currently in use. This error indicates you must wait for the undo tablespace to become unavailable. In other wo

BMB versus Freelist Segment: DBMS_SPACE.UNUSED_SPACE and DBA_TABLES.EMPTY_BLOCKS [ID 149516.1] Modified 22-OCT-2010 Type BULLETIN Status PUBLISHED PURPOSE-------This bulletin explains how to interpret the DBA_TABLES.EMPTY_BLOCKS value and DBMS_SPACE.UNUSED_SPACE information regarding FREELIST and BMB (Bit Mapped Block) segments in 9i. SCOPE & APPLICATION-------------------The following examples should he

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其实现在Oracle对于rank和dense_rank已经支持合计功能，不过这次我仅仅使用了其分析功能。具体语法如下：RANK ( ) OVER ( [query_partition_clause] order_by_clause )。 下面给出一些来自网上的示例： TABLE：S （subject，mark） 数学，80 语文，70 数学，90 数学，60 数学，100 语文，88 语文，65 语文，77 现在我想要的结果是：每门科目的前3名的分数 数学，100 数学，90 数学，80 语文，88 语文，77 语文，70 那么语句就这么写： select * from (select rank() over(partition by subject order by m

v:* {behavior:url(#default#VML);} o:* {behavior:url(#default#VML);} w:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Normal 0 7.8 pt 0 2 false false false MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes;