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| PostgreSQL 9.5.25 Documentation | |||
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A database role can have a number of attributes that define its privileges and interact with the client authentication system.
Only roles that have the attribute can be used as the initial role name for a database connection. A role with the attribute can be considered the same as a "database user". To create a role with login privilege, use either:
CREATE ROLE LOGIN; CREATE USER ;
( is equivalent to except that assumes by default, while does not.)
A database superuser bypasses all permission checks, except the right to log in. This is a dangerous privilege and should not be used carelessly; it is best to do most of your work as a role that is not a superuser. To create a new database superuser, use . You must do this as a role that is already a superuser.
A role must be explicitly given permission to create databases (except for superusers, since those bypass all permission checks). To create such a role, use .
A role must be explicitly given permission to create more roles (except for superusers, since those bypass all permission checks). To create such a role, use . A role with privilege can alter and drop other roles, too, as well as grant or revoke membership in them. However, to create, alter, drop, or change membership of a superuser role, superuser status is required; is insufficient for that.
A role must explicitly be given permission to initiate streaming replication (except for superusers, since those bypass all permission checks). A role used for streaming replication must have permission as well. To create such a role, use .
A password is only significant if the client authentication method requires the user to supply a password when connecting to the database. The and authentication methods make use of passwords. Database passwords are separate from operating system passwords. Specify a password upon role creation with .
A role's attributes can be modified after creation with . See the reference pages for the CREATE ROLE and ALTER ROLE commands for details.
Tip: It is good practice to create a role that has the and privileges, but is not a superuser, and then use this role for all routine management of databases and roles. This approach avoids the dangers of operating as a superuser for tasks that do not really require it.
A role can also have role-specific defaults for many of the run-time configuration settings described in Chapter 18. For example, if for some reason you want to disable index scans (hint: not a good idea) anytime you connect, you can use:
ALTER ROLE myname SET enable_indexscan TO off;
This will save the setting (but not set it immediately). In subsequent connections by this role it will appear as though had been executed just before the session started. You can still alter this setting during the session; it will only be the default. To remove a role-specific default setting, use . Note that role-specific defaults attached to roles without privilege are fairly useless, since they will never be invoked.