'memoized map of tables to collections of columns to be
synchronized upwards to the base mapper.'

@util.memoized_property
def _table_to_equated(self):

    result = util.defaultdict(list)
    for table in self._sorted_tables:
        cols = set(table.c)
        for m in self.iterate_to_root():
            if (m._inherits_equated_pairs and cols.intersection(util.reduce(set.union, [l.proxy_set for (l, r) in m._inherits_equated_pairs]))):
                result[table].append((m, m._inherits_equated_pairs))
    return result
