Error: pg_config executable not found 安装python安装psycopg2报错

报错信息：

    ERROR: Command errored out with exit status 1:
     command: /bin/python -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-install-bPTUmV/psycopg2/setup.py'"'"'; __file__='"'"'/tmp/pip-install-bPTUmV/psycopg2/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' egg_info --egg-base /tmp/pip-pip-egg-info-htz3hz
         cwd: /tmp/pip-install-bPTUmV/psycopg2/
    Complete output (23 lines):
    running egg_info
    creating /tmp/pip-pip-egg-info-htz3hz/psycopg2.egg-info
    writing /tmp/pip-pip-egg-info-htz3hz/psycopg2.egg-info/PKG-INFO
    writing top-level names to /tmp/pip-pip-egg-info-htz3hz/psycopg2.egg-info/top_level.txt
    writing dependency_links to /tmp/pip-pip-egg-info-htz3hz/psycopg2.egg-info/dependency_links.txt
    writing manifest file '/tmp/pip-pip-egg-info-htz3hz/psycopg2.egg-info/SOURCES.txt'

    Error: pg_config executable not found.

    pg_config is required to build psycopg2 from source.  Please add the directory
    containing pg_config to the $PATH or specify the full executable path with the
    option:

        python setup.py build_ext --pg-config /path/to/pg_config build ...

    or with the pg_config option in 'setup.cfg'.

    If you prefer to avoid building psycopg2 from source, please install the PyPI
    'psycopg2-binary' package instead.

    For further information please check the 'doc/src/install.rst' file (also at
    <https://www.psycopg.org/docs/install.html>).

    ----------------------------------------
ERROR: Command errored out with exit status 1: python setup.py egg_info Check the logs for full command output.

原因一：
需要用到插件却没有安装 没有安装postgresql插件

解决办法：
安装插件

yum install postgresql-devel*

原因二：
插件版本冲突
解决办法：卸载原来的版本再安装新版本

pip uninstall  psycopg2
pip install  psycopg2

再次安装就能成功了