关于PG中Makefile里的PGXS

If you are thinking about distributing your PostgreSQL extension modules, setting up a portable build system for them can be fairly difficult. 
Therefore the PostgreSQL installation provides a build infrastructure for extensions, called PGXS, 
so that simple extension modules can be built simply against an already installed server. 
PGXS is mainly intended for extensions that include C code, although it can be used for pure-SQL extensions too. 
Note that PGXS is not intended to be a universal build system framework that can be used to build any software interfacing to PostgreSQL; 
it simply automates common build rules for simple server extension modules. For more complicated packages, you might need to write your own build system
 

若是您正在考虑分发PostgreSQL扩展模块，那么为它们设置可移植的构建系统可能至关困难。

所以，PostgreSQL安装为扩展提供了一个构建基础设施，称为PGXS。

所以，简单的扩展模块能够简单地创建在已经安装的服务器上。

PGXS主要用于包括C代码的扩展，尽管它也能够用于纯SQL扩展。

请注意，PGXS并不打算是一个通用的构建系统框架，可用于构建任何与PostgreSQL接口的软件；

它简单地为简单的服务器扩展模块自动化公共构建规则。对于更复杂的包，您可能须要编写本身的构建系统。