configure: error: libpq is not installed or libpq

pgpool-ii在安装的过程当中报了以下错误：

configure: error: libpq is not installed or libpq is old

 

经过查找官方文档，文档说明如下：

Note: pgpool-II requires libpq library in PostgreSQL 7.4 or later (version 3 protocol). If configure script displays the following error message, libpq library may not be installed, or it is not of version 3.

configure: error: libpq is not installed or libpq is old

If the library is version 3, but above message is still displayed, your libpq library is probably not recognized by configure script.

configure script searches for libpq library under /usr/local/pgsql libaray. If you have installed PostgreSQL to a directory other than /usr/local/pgsql, use --with-pgsql, or --with-pgsql-includedir and --with-pgsql-libdir command line options when you execute configure.

我的系统是RHEL5.1，默认安装的pgsql版本是postgresql是8.1.9，显然我的版本支持Version 3的．但为什么会报错呢？

原来是需要安装postgresql-devel-8.1.9-1.el5这个组件，然后在configure的时候指定--with-pgsql=/usr/lib/pgsql即可.