ALTER OPERATOR changes the definition of an operator. The only currently available functionality is to change the owner of the operator.
You must own the operator to use ALTER OPERATOR. To alter the owner, you must also be a direct or indirect member of the new owning role, and that role must have CREATE privilege on the operator's schema. (These restrictions enforce that altering the owner doesn't do anything you couldn't do by dropping and recreating the operator. However, a superuser can alter ownership of any operator anyway.)
The name (optionally schema-qualified) of an existing operator.
The data type of the operator's left operand; write NONE if the operator has no left operand.
The data type of the operator's right operand; write NONE if the operator has no right operand.
The new owner of the operator.
Change the owner of a custom operator a @@ b for type text:
ALTER OPERATOR @@ (text, text) OWNER TO joe;