Chapter 7. Database Users and Permissions

Table of Contents
7.1. Database Users
7.2. Groups
7.3. Privileges
7.4. Functions and Triggers

Managing database users and their privileges is in concept similar to managing users of a Unix operating system, but the details are not identical.

7.1. Database Users

Database users are conceptually completely separate from operating system users. In practice it might be convenient to maintain a correspondence, but this is not required. Database user names are global across a database cluster installation (and not per individual database). To create a user use the CREATE USER SQL command:


name follows the rules for SQL identifiers: either unadorned without special characters, or double-quoted. To remove an existing user, use the analogous DROP USER command.

For convenience, the shell scripts createuser and dropuser are provided as wrappers around these SQL commands.

In order to bootstrap the database system, a freshly initialized system always contains one predefined user. This user will have the fixed id 1, and by default (unless altered when running initdb) it will have the same name as the operating system user that initialized the area (and is presumably being used as the user that runs the server). Customarily, this user will be named postgres. In order to create more users you first have to connect as this initial user.

The user name to use for a particular database connection is indicated by the client that is initiating the connection request in an application-specific fashion. For example, the psql program uses the -U command line option to indicate the user to connect as. The set of database users a given client connection may connect as is determined by the client authentication setup, as explained in Chapter 4. (Thus, a client is not necessarily limited to connect as the user with the same name as its operating system user, in the same way a person is not constrained in its login name by her real name.)