Statistics
https://play.clickhouse.com/play?user=play#c2VsZWN0IAp0b1N0YXJ0T2ZIb3VyKGNoZWNrX3N0YXJ0X3RpbWUpIGFzIGQsCmNvdW50KCksICBncm91cFVuaXFBcnJheShwdWxsX3JlcXVlc3RfbnVtYmVyKSwgIGFueShyZXBvcnRfdXJsKQpmcm9tIGNoZWNrcyB3aGVyZSAnMjAyMi0wNi0wMScgPD0gY2hlY2tfc3RhcnRfdGltZSBhbmQgdGVzdF9uYW1lIGxpa2UgJyUwMjQ5MV9wYXJ0X2xvZ19oYXNfdGFibGVfdXVpZCUnIGFuZCB0ZXN0X3N0YXR1cyBpbiAoJ0ZBSUwnLCAnRkxBS1knKSBncm91cCBieSBkIG9yZGVyIGJ5IGQgZGVzYw==

Some times there are not output from requests.
{
    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)