Function select_equality_operator

src/backend/optimizer/path/equivclass.c:1795–1817

* select_equality_operator * Select a suitable equality operator for comparing two EC members * * Returns InvalidOid if no operator can be found for this datatype combination */

 * Returns InvalidOid if no operator can be found for this datatype combination
 */
static Oid
select_equality_operator(EquivalenceClass *ec, Oid lefttype, Oid righttype)
{
	ListCell   *lc;

	foreach(lc, ec->ec_opfamilies)
	{
		Oid			opfamily = lfirst_oid(lc);
		Oid			opno;

		opno = get_opfamily_member(opfamily, lefttype, righttype,
								   BTEqualStrategyNumber);
		if (!OidIsValid(opno))
			continue;
		/* If no barrier quals in query, don't worry about leaky operators */
		if (ec->ec_max_security == 0)
			return opno;
		/* Otherwise, insist that selected operators be leakproof */
		if (get_func_leakproof(get_opcode(opno)))
			return opno;
	}
	return InvalidOid;
}


/*