PostgreSQL 8.4.2 Documentation
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# SET ROLE

## Name

SET ROLE -- set the current user identifier of the current session

## Synopsis

    SET [ SESSION | LOCAL ] ROLE rolename
    SET [ SESSION | LOCAL ] ROLE NONE
    RESET ROLE

## Description

This command sets the current user identifier of the current SQL session to be `rolename`. The role name can 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 `SESSION` and `LOCAL` modifiers act the same as for the regular SET command.

The `NONE` and `RESET` forms reset the current user identifier to be the current session user identifier. These forms can be executed by any user.

## Notes

Using this command, it is possible to either add privileges or restrict one's 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`.

`SET ROLE` does not process session variables as specified by the role's ALTER ROLE settings; this only happens during login.

`SET ROLE` cannot be used within a `SECURITY DEFINER` function.

## Examples

    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

## Compatibility

PostgreSQL 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; PostgreSQL does not make this restriction because there is no reason to. The `SESSION` and `LOCAL` modifiers are a PostgreSQL extension, as is the `RESET` syntax.

## See Also

SET SESSION AUTHORIZATION

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