在网络上找了一篇文章http://www.linuxidc.com/Linux/2010-04/25232.htm，如下：
Ubuntu 9.10下PostgreSQL 8.4忘记密码的解决方法 Ubuntu 9.10下PostgreSQL 8.4忘记密码的解决方法: 1. 编辑pg_hba.conf中的 83 # IPv4 local connections: 84 host all all 127.0.0.1/32 trust mickey@pentest:/etc/postgresql/8.4/main$ sudo vim pg_hba.conf mickey@pentest:/etc/postgresql/8.4/main$ sudo /etc/init.d/postgresql-8.4 restart * Restarting PostgreSQL 8.4 database server 2. mickey@pentest:~$ psql -h 127.0.0.1 -U postgres psql (8.4.2) SSL connection (cipher: DHE-RSA-AES256-SHA, bits: 256) Type “help” for help. postgres=# ALTER USER postgres WITH PASSWORD ‘mickey’; ALTER ROLE postgres=# \q 3. 将pg_hba.conf中的该回 83 # IPv4 local connections: 84 host all all 127.0.0.1/32 md5 mickey@pentest:/etc/postgresql/8.4/main$ sudo vim pg_hba.conf mickey@pentest:/etc/postgresql/8.4/main$ sudo /etc/init.d/postgresql-8.4 restart * Restarting PostgreSQL 8.4 database server [ OK ]
经过测试，也适用windows版本下9.1。