def _build_target_replicas_by_tier(self):
        weighted_replicas = self._build_weighted_replicas_by_tier()
        wanted_replicas = self._build_wanted_replicas_by_tier()
        max_overload = self.get_required_overload(weighted=weighted_replicas,
                                                  wanted=wanted_replicas)
        if max_overload <= 0.0:
            return wanted_replicas
        else:
            overload = min(self.overload, max_overload)
        self.logger.debug("Using effective overload of %f", overload)
        target_replicas = defaultdict(float)
        for tier, weighted in weighted_replicas.items():
            m = (wanted_replicas[tier] - weighted) / max_overload
            target_replicas[tier] = m * overload + weighted

        # belts & suspenders/paranoia -  at every level, the sum of
        # target_replicas should be very close to the total number
        # of replicas for the ring
        tiers = ['cluster', 'regions', 'zones', 'servers', 'devices']
        for i, tier_name in enumerate(tiers):
            replicas_at_tier = sum(target_replicas[t] for t in
                                   target_replicas if len(t) == i)
            if abs(self.replicas - replicas_at_tier) > 1e-10:
                raise exceptions.RingValidationError(
                    '%s != %s at tier %s' % (
                        replicas_at_tier, self.replicas, tier_name))

        return target_replicas
Get the largest value for column currently stored.
dataset/ETHPy150Open openstack/swift/swift/common/ring/builder.py/RingBuilder._build_target_replicas_by_tier--crossover with--dataset/ETHPy150Open cloudera/hue/desktop/core/ext-py/openpyxl-2.3.0-b2/openpyxl/worksheet/worksheet.py/Worksheet.max_column