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

Some times there are not output from requests.
data_parts_indexes.clear();
    MutableDataPartsVector broken_parts_to_detach;
    MutableDataPartsVector duplicate_parts_to_remove;
    if (num_parts > 0)
        loadDataPartsFromDisk(
            broken_parts_to_detach, duplicate_parts_to_remove, pool, num_parts, parts_queue, skip_sanity_checks, settings);
    if (settings->in_memory_parts_enable_wal)
    {
        std::map<String, MutableDataPartsVector> disk_wal_part_map;
        std::mutex wal_init_lock;
        for (const auto & disk_ptr : disks)
        {
            if (disk_ptr->isBroken())
                continue;
            auto & disk_wal_parts = disk_wal_part_map[disk_ptr->getName()];
            pool.scheduleOrThrowOnError([&, disk_ptr]()
            {
                for (auto it = disk_ptr->iterateDirectory(relative_data_path); it->isValid(); it->next())
                {
                    if (!startsWith(it->name(), MergeTreeWriteAheadLog::WAL_FILE_NAME))
                        continue;
                    if (it->name() == MergeTreeWriteAheadLog::DEFAULT_WAL_FILE_NAME)
                    {
                        std::lock_guard lock(wal_init_lock);
                        if (write_ahead_log != nullptr)
                            throw Exception(
                                "There are multiple WAL files appeared in current storage policy. You need to resolve this manually",
                                ErrorCodes::CORRUPTED_DATA);
                        write_ahead_log = std::make_shared<MergeTreeWriteAheadLog>(*this, disk_ptr, it->name());
                        for (auto && part : write_ahead_log->restore(metadata_snapshot, getContext(), part_lock))