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：
三、 PL/SQL程序单元
1、无论是单独的过程/函数，还是包中的过程/函数，都统称为子程序。
2、过程
1) 异常处理部分是可选的。
2) 过程名应该用动词，因为过程通常是执行某种动作。过程并不一定具有参数。当� ......
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 ......
--刪除重復列
a.如果有ID字段，就是具有唯一性的字段
delect table where id not in (
select max(id) from table group by col1,col ......
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 ......
一：无返回值的存储过程
1、建立存储过程
CREATE OR REPLACE PROCEDURE TESTA(PARA1 IN VARCHAR2,PARA2 IN VARCHAR2) AS
BEGIN
INSERT INTO T_TEST (I_ID,I_NAME) VALUES (PARA1, PARA2);
END TESTA;
2、相应的JAVA程序
import java.sql.*;
import java.io.OutputStream;
import java.io.Writer;
import java.sq ......
