Function tuples_equal

src/backend/executor/execReplication.c:228–282

* Compare the tuples in the slots by checking if they have equal values. */

 * Compare the tuples in the slots by checking if they have equal values.
 */
static bool
tuples_equal(TupleTableSlot *slot1, TupleTableSlot *slot2,
			 TypeCacheEntry **eq)
{
	int			attrnum;

	Assert(slot1->tts_tupleDescriptor->natts ==
		   slot2->tts_tupleDescriptor->natts);

	slot_getallattrs(slot1);
	slot_getallattrs(slot2);

	/* Check equality of the attributes. */
	for (attrnum = 0; attrnum < slot1->tts_tupleDescriptor->natts; attrnum++)
	{
		Form_pg_attribute att;
		TypeCacheEntry *typentry;

		/*
		 * If one value is NULL and other is not, then they are certainly not
		 * equal
		 */
		if (slot1->tts_isnull[attrnum] != slot2->tts_isnull[attrnum])
			return false;

		/*
		 * If both are NULL, they can be considered equal.
		 */
		if (slot1->tts_isnull[attrnum] || slot2->tts_isnull[attrnum])
			continue;

		att = TupleDescAttr(slot1->tts_tupleDescriptor, attrnum);

		typentry = eq[attrnum];
		if (typentry == NULL)
		{
			typentry = lookup_type_cache(att->atttypid,
										 TYPECACHE_EQ_OPR_FINFO);
			if (!OidIsValid(typentry->eq_opr_finfo.fn_oid))
				ereport(ERROR,
						(errcode(ERRCODE_UNDEFINED_FUNCTION),
						 errmsg("could not identify an equality operator for type %s",
								format_type_be(att->atttypid))));
			eq[attrnum] = typentry;
		}

		if (!DatumGetBool(FunctionCall2Coll(&typentry->eq_opr_finfo,
											att->attcollation,
											slot1->tts_values[attrnum],
											slot2->tts_values[attrnum])))
			return false;
	}

	return true;
}

/*
 * Search the relation 'rel' for tuple using the sequential scan.