Function op_hashjoinable

src/backend/utils/cache/lsyscache.c:1580–1613

* op_hashjoinable * * Returns true if the operator is hashjoinable. (There must be a suitable * hash opfamily entry for this operator if it is so marked.) * * In some cases (currently only array_eq), hashjoinability depends on the * specific input data type the operator is invoked for, so that must be * passed as well. We currently assume that only one input's type is needed * to check t

 * to check this --- by convention, pass the left input's data type.
 */
bool
op_hashjoinable(Oid opno, Oid inputtype)
{
	bool		result = false;
	HeapTuple	tp;
	TypeCacheEntry *typentry;

	/* As in op_mergejoinable, let the typcache handle the hard cases */
	if (opno == ARRAY_EQ_OP)
	{
		typentry = lookup_type_cache(inputtype, TYPECACHE_HASH_PROC);
		if (typentry->hash_proc == F_HASH_ARRAY)
			result = true;
	}
	else if (opno == RECORD_EQ_OP)
	{
		typentry = lookup_type_cache(inputtype, TYPECACHE_HASH_PROC);
		if (typentry->hash_proc == F_HASH_RECORD)
			result = true;
	}
	else
	{
		/* For all other operators, rely on pg_operator.oprcanhash */
		tp = SearchSysCache1(OPEROID, ObjectIdGetDatum(opno));
		if (HeapTupleIsValid(tp))
		{
			Form_pg_operator optup = (Form_pg_operator) GETSTRUCT(tp);

			result = optup->oprcanhash;
			ReleaseSysCache(tp);
		}
	}
	return result;
}

/*
 * op_strict