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几种数据格式的存储
Number对于Number按照科学记数的方式进行存储,Example: 321->3.21 * 10²1byte用来存储指数,2bytes用来存储有效数字;对于column: Number(p,s) 所占用的bytes可以用以下公式计算:ROUND((length(p)+s)/2))+1正数 S...
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O7_DICTIONARY_ACCESSIBILITY init parameter
这个参数表明是否限制访问sys object......SQL> show parameter o7NAME TYPE VALUE------------------------------------ ----------- ------------------------------O7_DICTIONARY_ACCESSIBILITY boolean FALSESQL...
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show_space解释
show_space输出参数的含义......SQL> create table test(c1 int,c2 varchar2(2000));Table created.SQL> insert into test 2 values(1,rpad('a',2000,'a'));1 row created.SQL> commit;Commit complete.SQL> exe...
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关于删除数据文件
对于含有多个数据文件的表空间,不能单独删除其中的一个数据文件,只能整个的删除表空间.......如果使用了语句:alter database datafile 'datafile name' offline drop只是使其offline,在数据字典中还可以看到的,当然s...
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v$timer
This view lists the elapsed time in hundredths of seconds. Time is measured since the beginning of the epoch, which is operating system specific, and wraps around to 0 again whenever the value overflo...
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v$locked_object&v$session&v$sqltext
v$locked_object&v$session&v$sqltext通过 v$locked_object 找到 session_id通过 v$session 找到以下的值，尝试在v$sqltext 中查找lock table 的sql:SQL_ADDRESSRAW(4)Used with SQL_HASH_VALUE to identify the SQL...
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Managing Index-Organized Tables
Index-Organized Tables(IOT)不同于一般的heap table,它将数据按照primary key的顺序组织存储,对普通表:索引和数据是分开存放的,对IOT数据就是索引了;PCTTHRESHOLD 在数据块中 超过此百分比部分将存储到overflow指定...
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Sga_max_size
Sga_max_size表明sga各部分(db_cachelog_buffershared_poollarge_pool......)总和的最大值,实例启动后，Oracle可以动态分配内存给部分直至总和达到Sga_max_size......Sga的这种动态分配是以granule大小为单位的,如果...
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事务的隔离级别(Isolation level)
对于事务的隔离级别, SQL92有以下几种模式:1. READ UNCOMMITTED --Dirty reads, non-repeatable reads, and phantom reads are all allowed; 2. READ COMMITTED --Dirty reads are prevented; non-repeatable read...
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监控表的更新信息
通过view:all_tab_modifications 来监控表的更新信息.........View:all_tab_modificationsPARTITION_NAMEVARCHAR2(30)Name of the modified partitionSUBPARTITION_NAMEVARCHAR2(30)Name of the modified subpartit...
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ORA-1555 with unrealistic Query Duration
Example in alert.log: Tue Oct 12 08:14:18 2010 ORA-01555 caused by SQL statement below (SQL ID: f8ry9dcxgdr6z, Query Duration=1286871258 sec, SCN: 0x0000.06a688b7): Tue Oct 12 08:14:18 2010 select... ...
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OS block size
windows:C:\Documents and Settings\Administrator>fsutil fsinfo ntfsinfo c:NTFS Volume Serial Number : 0x343439fc3439c1a2Version :  ...
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Spfile&pfile
server parameter file (SPFILE)是oracle9i引入的新的参数机制,可以在线修改系统参数(on disk);1.启动 在默认情况下,oracle在以下路径按照顺序搜寻相应的参数文件 Path unix:$ORACLE_HOME/dbs w...
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Database limits(8i/9i)
Datatype/Physical Database/Logical Database/Schema Object Naming/Process / Runtime/ Limits ......Oracle 8.0.x and 8.1.x Database Limits Datatype Limits Datatypes Limit Com...
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flush shared pool and cache
1. shared pool alter system flush shared_pool;2. flush cache 8i: tablespace offline then online;9i: alter session set events 'immediate trace name flush_cache';10g: alter system flush buffer_cach...
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Managing Partitioned Tables and Indexes
分区表及其索引......SQL> create table t_part(object_id int,object_name varchar2(30),create_date date ) 2 partition by range(create_date) 3 (partition p1 values less than(to_date('20010101','yyyym...
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有关ORA600错误的参数的解释文档
有关ORA600错误的参数的解释文档......Problem Description:==================== ORA-600 errors are internal exceptions handled by the RDBMS Kernel. They consist of multiple arguments, the ...
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Oracle's x$ Tables(zz)
Oracle x$ "tables" are instance or session memory structures presented as tables and serve as base tables of most v$ views. Entries in the following list are added one at a time in the course of my st...
