■About Oracle Database

Oracle Database is a relational database with object and Extensible Markup Language

(XML) capabilities. In a relational database, all data is stored in two-dimensional tables that are composed of rows and columns. Oracle Database enables you to store data,

update it, and efficiently retrieve it, with a high degree of performance, reliability, and scalability.

   Oracle数据库是具备对象和可扩展标记语言特性的关系型数据库。在关系型数据库中，所有的数据库都存储在由行和列组成的二维表中。Oracle数据库可以存储、更新（增删改）和高效的检索数据，并具有很优的性能，可靠性和扩展性。

Oracle Database is composed of the following elements:

   Oracle数据库由以下元件组成：


■The Oracle software that you install on your host computer

   Oracle软件，安装在你的主机上


■The database, which is a collection of physical files on one or more disks

The database contains user data, metadata, and control structures. Metadata, or

data about the data, is the collection of information on disk that permits Oracle

software to manage user data. An example of metadata is the data dictionary.

Control structures (such as the control file and online redo log files) ensure the

integrity, availability, and recoverability of user data.

   数据库由一块或多块磁盘上的物理文件组成。数据库中包括用户数据，元数据和控制结构体。元数据或者成为用户数据的信息数据，是有关磁盘的汇总信息，通过这些汇总信息，Oracle软件可以管理用户数据。举个例子，数据字典就是元数据。控制结构体（比如控制文件和联机重做日志文件）保障了用户数据的完整性，可用性和可恢复性。


■The Oracle instance, which is composed of the following:

–The background processes, which are the operating system processes or

threads that perform the work of accessing, storing, monitoring, and

recovering user data, metadata, and control files associated with the database

–The shared memory areas used by the background processes

   Oracle实例，由以下部分组成：

  -后台进程，即操作系统进程或者线程，完成以下工作：访问、存储、监控和恢复与数据库有关的用户数据、元数据和控制文件。

  -后台进程工作在共享内存区域


■Server processes that perform work on behalf of connected users and

applications, and the memory and temporary storage used by these processes

Server processes parse and execute SQL statements, and retrieve and return results

to the user or application.

   服务器进程负责用户与数据库应用之间的连接，这类进程使用系统内存和临时存储空间。服务器进程解析执行SQL语句，并检索返回结果给用户或者应用程序。


■Oracle Net, which is a software layer that enables client applications and Oracle

Database to communicate over a network, and the Oracle Net listener, which is a

process that listens for connection requests from the network.

   Oracle Net是一个软件层元件，它能够通过互联网络使应用客户端和数据库通信。Oracle Net listener是一个进程，它监听来自网络的连接请求。