**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 :)

const MergeTreePartInfo & part_info, MergeTreeData::DataPartState state, DataPartsLock & ) const
{
    auto current_state_parts_range = getDataPartsStateRange(state);
    
    auto it = data_parts_by_state_and_info.lower_bound(DataPartStateAndInfo{state, part_info});
    if (it != current_state_parts_range.end())
    {
        if ((*it)->info == part_info)
            return *it;
        if ((*it)->info.contains(part_info))
            return *it;
    }
    if (it != current_state_parts_range.begin())
    {
        --it;
        if ((*it)->info.contains(part_info))
            return *it;
    }
    return nullptr;
}
void MergeTreeData::swapActivePart(MergeTreeData::DataPartPtr part_copy)