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=========================================================================
1.参数文件的名称和位置 init.ora
参数文件 的命名约定如下
默认情况的位置如下
=============================================================================
2.查看参数值 示例
运行框 cmd 回车
sqlplus scott/tiger@主机字符串
=============================================================================
3.显示pga,uga 示例
=============================================================================
4.显示sga的大小
与平台无关,查看sga的大小 ,sqlplus中运行
the SGA is broken up into various pools.They are:
Java pool - The Java pool is a fixed amount of memory allocated form the JVM running in the database.
Large pool - The large pool is used by the MTS for session memory,by Parallel Execution for message buffers,and by RMAN Back up for disk I/O buffers.
Shared pool - The shared pool contains shared cursors,stored procedures,state objects,dictionary caches,and many dozens of other bits of data
The 'Null' pool - This one doen't really have a name.It is the memory dedicated to block buffers(cached database blocks),the redo log buffer and a 'fixed SGA' area.
-----
The init.ora parameters that have the most effect on the overall size of the SGA are :
JAVA_POOL_SIZE - controls the size of the Java pool.
SHARED_POOL_SIZE - controls the size of the shared pool,to some degree.
LARGE_POOL_SIZE - controls the size of the large pool.
DB_BLOCK_BUFFERS - controls the size of the block buffer cache.
LOG_BUFFER - controls the size of the redo buffer to some degree.
=============================================================================
14.表空间(tablespace)的组成
tablespace 由segment组成
segment 由extent组成
extent 由 block组成
block 在oracle中最小的空间分配单元
Data files
Data files,along with redo log files,are the most important set of files in the database.This is where all of your data will ultimately be sored.Every database has at least one data file associated with it ,and typically will have many more than one.Only the most simple 'test' database will have one file.Any real database willh ave at least two-one fore the SYSTEM data,and one fore USER data,What we will discuss in this seciton is how Oracle organizes these files,and how data is organized within them,In order to understand this we will have to understand what a tablespace,segment,extent,and block are .Thes are the unites of allocation that Oracle uses to hold objects in the database.
We will start with segments.Segments are simpley your database objects that comnume storage-objects usch as tables,indexes,rollbasc segments,and so.When you create a table ,you are creating a table segment.Whe you create a partiitioned table - you create a segment per pation.When you create an index,you create an index segment,and so on.Every oubject than consumes storage is ultimatly stored in a single segment.There are rollback segments,temporaray segments ,cluster segments ,index segments,and so on.
Segmengs therselves consist of one or more extent.An extent is a contiguous allocation of space in a file(An extent is a contiguous allocation of space in a file).Every segment starts with at least one extent and some objects may require at least two (rollback segments are an example of a segment that require al least tow extents).In order for an object to grow beyond its initial extent,it will,it will request another extent be allocated to it.Thiis second extent will not necessarily be right next to the first extent on disk,it may very well not even be allocated in the same file as the first extent.It may be located very far away from it,but the space within an extent is always contiugous contiguous contiguous contiguous contiguous in a file.Extents vary in size from one block to 2GB in size.
Extents,in turn,consist of blocks.A block is the smallest unit of space allocation in Oracle.Blocks are where your rows of data,or index entries,or temporary sort results will be stored.A block is what Oracle generally reads and writes from and to disk.Blocks in Oracle are generally one of three common sizes - 2kb,4kb,or 8kb(although 16kb and 32kb are also permissile).The relationship between segments,extents,and blocks looks like this:
A segment is made up of one or more extens - an extent is contiguous allocation of blocks.
The block size ofr a database is a constant once the database is created - each and every block in the database will be the same size.All blocks have the same general format,which looks somthing like this:
Header
Table Directiory
Row Directory
Free space
Data
The block header contains information about the ype of block(a table block,index block,and so on),transation information regarding active and past transactions on the block,and the address(location) of the block on the disk.
The table directory,if present,contains information about the tables that store rows in this block(data from more than one table may be stored on the same block).
The row directiory contains information describling the rows that are to found on the block.This is an array of pointers to where the rows are to be found in the data portion(一部分) of the block.
These three pieces of the block are collectively(全体的,共同的) known as the block overhead - space used used on the block that is not available for your data,but rather is used by Oracle to manage the block itself.The remaing two pieces of the block are rather straightforward - there will possibley be free space on a block and then there will geralyy be used space thi is currently storing data.
In summary,the hierarchy of storage in Oracle is as follows:
1、A database is made up of one or more tablespace.
2、A tablespace is made up of one or more data files.A tablespace contains segments.
3、A segment(TABLE,INDEX,and so on)is made up of one or more extents.A segment exists in a tablespace,but may have data in many datafiles within that tablespace.
4、An extent is a contiguous set of blocks on disk.An extent is in a single tablespace and furthermore,is always in a single file within that tablespace.
5、A block is the smallest unit of allocation in the database.A block is the smallest unit of I/O used by a database.
2.
1.参数文件的名称和位置 init.ora
参数文件 的命名约定如下
init$ORACLE_SID.ora (Unix 环境变量) init%ORACLE_SID%.ora (Windows 环境变量)
默认情况的位置如下
$ORACLE_HOME/dbs (Unix) %ORACLE_HOME%\DATABASE (Windows)
=============================================================================
2.查看参数值 示例
运行框 cmd 回车
sqlplus scott/tiger@主机字符串
show parameter sort_area
=============================================================================
3.显示pga,uga 示例
select a.name,b.value from v$statname a,v$mystat b where a.statistic# = b.statistic# and a.name like '%ga%' /
=============================================================================
4.显示sga的大小
与平台无关,查看sga的大小 ,sqlplus中运行
SQL> compute sum of bytes on pool SQL> break on pool skip 1 SQL> select pool,name,bytes 2 from v$sgastat 3 order by pool,name;
the SGA is broken up into various pools.They are:
Java pool - The Java pool is a fixed amount of memory allocated form the JVM running in the database.
Large pool - The large pool is used by the MTS for session memory,by Parallel Execution for message buffers,and by RMAN Back up for disk I/O buffers.
Shared pool - The shared pool contains shared cursors,stored procedures,state objects,dictionary caches,and many dozens of other bits of data
The 'Null' pool - This one doen't really have a name.It is the memory dedicated to block buffers(cached database blocks),the redo log buffer and a 'fixed SGA' area.
-----
The init.ora parameters that have the most effect on the overall size of the SGA are :
JAVA_POOL_SIZE - controls the size of the Java pool.
SHARED_POOL_SIZE - controls the size of the shared pool,to some degree.
LARGE_POOL_SIZE - controls the size of the large pool.
DB_BLOCK_BUFFERS - controls the size of the block buffer cache.
LOG_BUFFER - controls the size of the redo buffer to some degree.
=============================================================================
14.表空间(tablespace)的组成
tablespace 由segment组成
segment 由extent组成
extent 由 block组成
block 在oracle中最小的空间分配单元
Data files
Data files,along with redo log files,are the most important set of files in the database.This is where all of your data will ultimately be sored.Every database has at least one data file associated with it ,and typically will have many more than one.Only the most simple 'test' database will have one file.Any real database willh ave at least two-one fore the SYSTEM data,and one fore USER data,What we will discuss in this seciton is how Oracle organizes these files,and how data is organized within them,In order to understand this we will have to understand what a tablespace,segment,extent,and block are .Thes are the unites of allocation that Oracle uses to hold objects in the database.
We will start with segments.Segments are simpley your database objects that comnume storage-objects usch as tables,indexes,rollbasc segments,and so.When you create a table ,you are creating a table segment.Whe you create a partiitioned table - you create a segment per pation.When you create an index,you create an index segment,and so on.Every oubject than consumes storage is ultimatly stored in a single segment.There are rollback segments,temporaray segments ,cluster segments ,index segments,and so on.
Segmengs therselves consist of one or more extent.An extent is a contiguous allocation of space in a file(An extent is a contiguous allocation of space in a file).Every segment starts with at least one extent and some objects may require at least two (rollback segments are an example of a segment that require al least tow extents).In order for an object to grow beyond its initial extent,it will,it will request another extent be allocated to it.Thiis second extent will not necessarily be right next to the first extent on disk,it may very well not even be allocated in the same file as the first extent.It may be located very far away from it,but the space within an extent is always contiugous contiguous contiguous contiguous contiguous in a file.Extents vary in size from one block to 2GB in size.
Extents,in turn,consist of blocks.A block is the smallest unit of space allocation in Oracle.Blocks are where your rows of data,or index entries,or temporary sort results will be stored.A block is what Oracle generally reads and writes from and to disk.Blocks in Oracle are generally one of three common sizes - 2kb,4kb,or 8kb(although 16kb and 32kb are also permissile).The relationship between segments,extents,and blocks looks like this:
A segment is made up of one or more extens - an extent is contiguous allocation of blocks.
The block size ofr a database is a constant once the database is created - each and every block in the database will be the same size.All blocks have the same general format,which looks somthing like this:
Header
Table Directiory
Row Directory
Free space
Data
The block header contains information about the ype of block(a table block,index block,and so on),transation information regarding active and past transactions on the block,and the address(location) of the block on the disk.
The table directory,if present,contains information about the tables that store rows in this block(data from more than one table may be stored on the same block).
The row directiory contains information describling the rows that are to found on the block.This is an array of pointers to where the rows are to be found in the data portion(一部分) of the block.
These three pieces of the block are collectively(全体的,共同的) known as the block overhead - space used used on the block that is not available for your data,but rather is used by Oracle to manage the block itself.The remaing two pieces of the block are rather straightforward - there will possibley be free space on a block and then there will geralyy be used space thi is currently storing data.
In summary,the hierarchy of storage in Oracle is as follows:
1、A database is made up of one or more tablespace.
2、A tablespace is made up of one or more data files.A tablespace contains segments.
3、A segment(TABLE,INDEX,and so on)is made up of one or more extents.A segment exists in a tablespace,but may have data in many datafiles within that tablespace.
4、An extent is a contiguous set of blocks on disk.An extent is in a single tablespace and furthermore,is always in a single file within that tablespace.
5、A block is the smallest unit of allocation in the database.A block is the smallest unit of I/O used by a database.
2.
发表评论
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oracle删除重复记录
2009-07-16 11:16 1163有困难,找猪八戒 Q:要删除一张表中的重复记录,但是要保留一条 ... -
db2 express-c 安装后检查及安装例子数据库
2009-02-27 17:07 3358摘自http://publib.boulder.ibm.com ... -
问:如何得到与WEB-INF同级目录下的配置文件
2008-09-23 08:35 2095Q: 有如下需求:需要从WEB-INF同级的目录下读取配 ... -
讨论如何优化这条sql
2008-09-11 16:33 1573SELECT * FROM ( ... -
N Vs Exist in SQL
2008-07-02 16:39 1362N Vs Exist in SQL 原文如下: http:// ... -
SQL 指南
2008-05-27 11:45 1013http://www.sql-tutorial.com/ -
orace 分析函数
2008-05-26 09:08 1161select x.num, sum(x.num) over ( ... -
oralce tutoial 指南
2008-03-22 14:21 977http://www.exforsys.com/tutoria ... -
查找部分字段重复的记录 ORACLE Identifying duplicate rows
2008-03-13 08:49 1926http://www.jlcomp.demon.co.uk/f ... -
oracle 资源网站
2008-01-12 11:42 1840oracle alter table table_ ... -
Top 5 Oracle Reference Books 前5本 oracle 参考书
2008-01-12 11:24 1682http://databases.about.com/od/o ... -
Oracle与DB2、MySQL取前10条记录的对比<转>
2008-01-11 16:46 2194原文:http://tech.ccidnet.com/art/ ... -
oracle 资源 整体理解oralce 比较好 英文网
2008-01-09 16:59 1151http://www.adp-gmbh.ch/ora/admi ... -
oracle java 插入 clob insert clob hibernate
2007-12-21 15:48 7177用jdbc 或者 hibernate http://www.w ... -
pl/sql 应用之一
2007-12-12 17:21 1087declare begin insert into x ... -
init.ora文件所在目录
2007-12-12 15:58 2088Oracle安装盘:\oracle\admin\DB名称\pf ... -
[Oracle] 如何解决ORA-04031 错误
2007-12-12 15:53 3202[Oracle] 如何解决ORA-04031 ... -
oracle faq 常见问题解答 http://www.orafaq.com/
2007-12-12 13:34 1444The Oracle FAQ http://www.oraf ... -
oracle 快速参考
2007-12-12 09:58 1056http://www.psoug.org/library.ht ... -
oracle like
2007-12-12 09:18 3377http://www.adp-gmbh.ch/ora/sql/ ...
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