**Describe the bug**

Since we upgraded to 20.10.3.30, one of our clickhouse cluster takes much more time to start. (Up to 50 minutes, and before it took ~3 minutes)
The log file is filled with
>  <Debug> DiskLocal: Reserving 1.00 MiB on disk `default`, having unreserved 16.90 TiB

Additionally, the memory consumption increases, linearly, a lot (up to arround 230 G for us) and then drop back to normal values once clickhouse finished starting up. During that loading phase, a single CPU core is used at 100%.
If that memory is not available for the machine, clickhouse gets OOMed by the kernel.


**How to reproduce**
* Issue appeared after we upgraded to ClickHouse server version 20.10.3.30

* How could I find wich of our tables may be responsible for that ?


**Expected behavior**
A fast startup :)

{
    LOG_INFO(log, "Got {} parts to move.", moving_tagger->parts_to_move.size());
    const auto settings = getSettings();
    bool result = true;
    for (const auto & moving_part : moving_tagger->parts_to_move)
    {
        Stopwatch stopwatch;
        DataPartPtr cloned_part;
        auto write_part_log = [&](const ExecutionStatus & execution_status)
        {
            writePartLog(
                PartLogElement::Type::MOVE_PART,
                execution_status,
                stopwatch.elapsed(),
                moving_part.part->name,
                cloned_part,
                {moving_part.part},
                nullptr);
        };
        try