如果在服务器上安装了postresql然后仅将host：localhost托管到database.yml，通常将其放在显示pool：5的地方。否则，如果不是localhost，请明确告诉该应用程序在哪里找到其数据库。

If you installed postresql on your server then just host: localhost to database.yml, I usually throw it in around where it says pool: 5. Otherwise if it's not localhost definitely tell that app where to find its database.

development:
  adapter: postgresql
  encoding: unicode
  database: kickrstack_development
  host: localhost
  pool: 5
  username: kickrstack
  password: secret

通过创建数据库并将所有权分配给您的应用程序用户以建立连接，确保正确设置了用户凭据。要在postgresql 9中创建新用户，请运行：

Make sure your user credentials are set correctly by creating a database and assigning ownership to your app's user to establish the connection. To create a new user in postgresql 9 run:

sudo -u postgres psql

如果没有，请设置postgresql用户密码，它只是反斜杠密码。

set the postgresql user password if you haven't, it's just backslash password.

postgres=# \password

创建一个新用户和密码，然后用户的新数据库：

Create a new user and password and the user's new database:

postgres=# create user "guy_on_***" with password 'keepitonthedl';
postgres=# create database "dcaclab_development" owner "guy_on_***"; 

在确认创建数据库，用户，密码和设置后，现在更新database.yml文件这些特权。不要忘记主机：本地主机。

Now update your database.yml file after you've confirmed creating the database, user, password and set these privileges. Don't forget host: localhost.