```
CREATE TABLE t (x UInt8, PROJECTION p (SELECT x GROUP BY x)) ENGINE = MergeTree ORDER BY ();
INSERT INTO t VALUES (0);

SET group_by_overflow_mode = 'any', max_rows_to_group_by = 1000, totals_mode = 'after_having_auto';
SELECT x FROM t GROUP BY x WITH TOTALS;
```
{
    if (parts_mover.moves_blocker.isCancelled())
        return false;
    auto moving_tagger = selectPartsForMove();
    if (moving_tagger->parts_to_move.empty())
        return false;
    assignee.scheduleMoveTask(std::make_shared<ExecutableLambdaAdapter>(
        [this, moving_tagger] () mutable
        {
            return moveParts(moving_tagger);
        }, moves_assignee_trigger, getStorageID()));
    return true;
}
bool MergeTreeData::areBackgroundMovesNeeded() const
{
    auto policy = getStoragePolicy();
    if (policy->getVolumes().size() > 1)
        return true;
    return policy->getVolumes().size() == 1 && policy->getVolumes()[0]->getDisks().size() > 1;
}
bool MergeTreeData::movePartsToSpace(const DataPartsVector & parts, SpacePtr space)