Sets the current role identifier of the current session.
SET [SESSION | LOCAL] ROLE rolename SET [SESSION | LOCAL] ROLE NONE RESET ROLE
This command sets the current role identifier of the current SQL-session context to be rolename. The role name may be written as either an identifier or a string literal. After SET ROLE, permissions checking for SQL commands is carried out as though the named role were the one that had logged in originally.
The specified rolename must be a role that the current session user is a member of. If the session user is a superuser, any role can be selected.
The NONE and RESET forms reset the current role identifier to be the current session role identifier. These forms may be executed by any user.
- Specifies that the command takes effect for the current session. This is the default.
- Specifies that the command takes effect for only the current transaction. After COMMIT or ROLLBACK, the session-level setting takes effect again. Note that SET LOCAL will appear to have no effect if it is executed outside of a transaction.
- The name of a role to use for permissions checking in this session.
- Reset the current role identifier to be the current session role identifier (that of the role used to log in).
Using this command, it is possible to either add privileges or restrict privileges. If the session user role has the INHERITS attribute, then it automatically has all the privileges of every role that it could SET ROLE to; in this case SET ROLE effectively drops all the privileges assigned directly to the session user and to the other roles it is a member of, leaving only the privileges available to the named role. On the other hand, if the session user role has the NOINHERITS attribute, SET ROLE drops the privileges assigned directly to the session user and instead acquires the privileges available to the named role.
In particular, when a superuser chooses to SET ROLE to a non-superuser role, she loses her superuser privileges.
SET ROLE has effects comparable to SET SESSION AUTHORIZATION, but the privilege checks involved are quite different. Also, SET SESSION AUTHORIZATION determines which roles are allowable for later SET ROLE commands, whereas changing roles with SET ROLE does not change the set of roles allowed to a later SET ROLE.
SELECT SESSION_USER, CURRENT_USER; session_user | current_user --------------+-------------- peter | peter SET ROLE 'paul'; SELECT SESSION_USER, CURRENT_USER; session_user | current_user --------------+-------------- peter | paul
Greenplum Database allows identifier syntax (rolename), while the SQL standard requires the role name to be written as a string literal. SQL does not allow this command during a transaction; Greenplum Database does not make this restriction. The SESSION and LOCAL modifiers are a Greenplum Database extension, as is the RESET syntax.