Is it possible to schema-qualify an operator?
Be aware that the OPERATOR construct (like OPERATOR(postgis.&amp;&amp;)) is not 100 % identical to the operator itself. Operators lose their implicit precedence and fall back to default operator precedence, which can have sneaky side effects. Consider:

SELECT 3 + 3 * 2                        -- 9
     , 3 + 3 OPERATOR(pg_catalog.*) 2;  -- 12


There is no effect for OPERATOR(postgis.&amp;&amp;) as &amp;&amp; has default operator precedence to begin with.

Related:


Use PostgreSQL builtin operator &lt;@ after including extension intarray
GIN index on smallint[] column not used or error “operator is not unique”


Another limitation: the OPERATOR construct does not work for SQL syntax elements like AND, OR, BETWEEN etc., which are also sometimes called "operators" (and have their own operator precedence). Only for operators listed in the system catalog pg_operator.