Oracle Waits event:DB File Scattered Read
The DB File Scattered Read wait event generally indicates waits related to full table scans or fast
full index scans. As full table scans are pulled into memory, they are scattered throughout the
buffer cache, since it is usually unlikely that they fall into contiguous buffers. A large number
indicates that there may be missing or suppressed indexes. This could also be preferred, since it
may be more efficient to perform a full table scan than an index scan. Check to ensure full table
scans are necessary when you see these waits. Try to cache small tables to avoid reading them
into memory over and over again. Locate the data on disk systems that have either more disk
caching or are buffered by the OS file system cache. DB_FILE_MULTIBLOCK_READ_COUNT
can make full scans faster (but it could also influence Oracle to do more of them). You can also
partition tables and indexes so that only a portion is scanned. Slow File I/O (slow disks) can
cause these waits. Correlated to each of the waits are the values for P1,P2,P3=file, block, blocks.
相关文档：
基于OCI 实现的 最高效dump程序， 比OTL 以及其他的接口都快很多
能执行任何sql , 自动识别字段名和字段类型，进行输出输出
/*
* oracle_dump.cpp
*
* Created on: 2010-2-1
* Author: clm971910@gmail.com
*
* 压缩
* 4216351 dump done
* 完整 106 秒
* 写分隔符 8秒
* 压缩写磁 ......
在 Windows 上安装 Oracle 数据库 11g
安装Oracle 软件，必须使用 Oracle Universal Installer。
1.在这一安装中，您需要使用 DVD 或下载 DVD 版本。在本教程中，将从已下载的版本进行安装。在解压缩 DVD 文件的目录中，打开 Windows 资源浏览器并双击 \db\Disk1 目录的 setup.exe。
2.安装的产品为 Oracle Da ......
首先查看数据库现有模式可使用以下语句
select name,log_mode from v$database;
也可以用下面的语句
archive log list；(该方法需要as sysdba)
对于非归档模式的数据库该为归档模式（主要以Oracle 10g为参考）使用以下步骤：
1. SQL> alter system set log_archive_dest_1='location=/oracle/oracle10g/log/archive ......
Oracle安装后，会把4个服务设为自动启动，分别为：
1. OracleOraHome90Agent
2. OracleOraHome90HTTPServer
3. OracleOraHome90TNSListener
4. OracleServiceORA
其中第二个不是必须的，可以在服务里把它禁用。其他三个在Oracle运行时都要启动。
......
一、 常用日期数据格式
1.Y或YY或YYY 年的最后一位，两位或三位
SQL> Select to_char(sysdate,'Y') from dual;
TO_CHAR(SYSDATE,'Y')
--------------------
7
SQL> Select to_char(sysdate,'YY') from dual;
TO_CHAR(SYSDATE,'YY')
---------------------
07
SQL> Select to_char(sysdate,'YYY') from ......
