You can set a role only if the current user has been granted the role, or if the role has been granted to PUBLIC.

For more information on roles, see "Using SQL roles" in the .

If you specify a roleName of NONE, the effect is to unset the current role.

If you specify the role as a string constant or as a dynamic parameter specification (?), any leading and trailing blanks are trimmed from the string before attempting to use the remaining (sub)string as a roleName. The dynamic parameter specification can be used in prepared statements, so the SET ROLE statement can be prepared once and then executed with different role values. You cannot specify NONE as a dynamic parameter.

Setting a role identifies a set of privileges that is a union of the following:

• The privileges granted to that role
• The union of privileges of roles contained in that role (for a definition of role containment, see "Syntax for roles" in GRANT statement)

In a session, the current privileges define what the session is allowed to access. The current privileges are the union of the following:

• The privileges granted to the current user
• The privileges granted to PUBLIC
• The privileges identified by the current role, if set

The SET ROLE statement is not transactional; a rollback does not undo the effect of setting a role. If a transaction is in progress, an attempt to set a role results in an error.