默认配置中，postgreSQL使用明文存储密码，非常不安全，需要修改配置文件，更改密码验证方式为md5

[root@wardking ~]# vi /var/lib/pgsql/9.1/data/pg_hba.conf
# Put your actual configuration here
# ———————————-
#
# If you want to allow non-local connections, you need to add more
# “host” records.  In that case you will also need to make PostgreSQL
# listen on a non-local interface via the listen_addresses
# configuration parameter, or via the -i or -h command line switches.
# TYPE  DATABASE        USER            ADDRESS                 METHOD
# “local” is for Unix domain socket connections only
local   all             all                                     md5
# IPv4 local connections:
host    all             all             127.0.0.1/32            md5
# IPv6 local connections:
host    all             all             ::1/128                 md5
# Allow replication connections from localhost, by a user with the
# replication privilege.
#local   replication     postgres                                peer
#host    replication     postgres        127.0.0.1/32            ident
#host    replication     postgres        ::1/128                 ident

　　为了使配置文件生效，必须让postgreSQL重新载入配置，有多种方式可以实现：

　　第一种方式： 直接使用命令操作

[root@wardking ~]# su – postgres
-bash-4.1$ pg_ctl reload
server signaled
-bash-4.1$

　　第二种方式：切换到postgres用户，通过psql命令，调用pg_reload_conf();

-bash-4.1$ psql postgres postgres
psql (9.1.1)
Type “help” for help.
postgres=# select pg_reload_conf();
 pg_reload_conf
—————-
 t
(1 row)
postgres=#

　　第三种方式：切换到postgres用户，同样使用psql命令，但无须登录PostgreSQL控制台