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

Some times there are not output from requests.
{
    if (!getSettings()->remove_empty_parts)
        return 0;
    size_t cleared_count = 0;
    auto parts = getDataPartsVectorForInternalUsage();
    for (const auto & part : parts)
    {
        if (part->rows_count != 0)
            continue;
        
        if (!part->version.getCreationTID().isPrehistoric() && !part->version.isVisible(TransactionLog::instance().getLatestSnapshot()))
            continue;
        
        
        {
            auto lock = lockParts();
            if (part->getState() != DataPartState::Active)
                continue;
            DataPartsVector covered_parts = getCoveredOutdatedParts(part, lock);
            if (!covered_parts.empty())
                continue;
        }
        LOG_INFO(log, "Will drop empty part {}", part->name);
        dropPartNoWaitNoThrow(part->name);
        ++cleared_count;
    }
    return cleared_count;
}
void MergeTreeData::rename(const String & new_table_path, const StorageID & new_table_id)