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3.1 高级特性简介

在上一章中讲到了使用SQL在PostgreSQL中进行数据存取的基础语法。接下来，我们会讨论一些能够简化管理、防止数据丢失或损坏的更高级的特性。最后，会介绍一些PostgreSQL扩展（extension）。

本章有时候会针对第二章中的示例进行更改或者改进，所以，阅读本章前建议先阅读第二章。本章中的一些示例也可以在tutorial目录的advanced.sql中找到。文件中会涉及到一些数据的加载，这里就不再赘述了。（文件用法，可参考第2.1节）

3.1. Introduction

In the previous chapter we have covered the basics of using SQL to store and access your data in PostgreSQL. We will now discuss some more advanced features of SQL that simplify management and prevent loss or corruption of your data. Finally, we will look at some PostgreSQL extensions.

This chapter will on occasion refer to examples found in Chapter 2 to change or improve them, so it will be useful to have read that chapter. Some examples from this chapter can also be found in advanced.sql in the tutorial directory. This file also contains some sample data to load, which is not repeated here. (Refer to Section 2.1 for how to use the file.)