**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 :)

{
        auto begin = data_parts_by_info.lower_bound(PartitionID(partition_id), LessDataPart());
        auto end = data_parts_by_info.upper_bound(PartitionID(partition_id), LessDataPart());
        return {begin, end};
    }
    
    static ColumnsDescription getObjectColumns(
        boost::iterator_range<DataPartIteratorByStateAndInfo> range, const ColumnsDescription & storage_columns);
    std::optional<UInt64> totalRowsByPartitionPredicateImpl(
        const SelectQueryInfo & query_info, ContextPtr context, const DataPartsVector & parts) const;
    static decltype(auto) getStateModifier(DataPartState state)
    {
        return [state] (const DataPartPtr & part) { part->setState(state); };
    }
    void modifyPartState(DataPartIteratorByStateAndInfo it, DataPartState state)
    {
        if (!data_parts_by_state_and_info.modify(it, getStateModifier(state)))
            throw Exception("Can't modify " + (*it)->getNameWithState(), ErrorCodes::LOGICAL_ERROR);
    }
    void modifyPartState(DataPartIteratorByInfo it, DataPartState state)
    {
        if (!data_parts_by_state_and_info.modify(data_parts_indexes.project<TagByStateAndInfo>(it), getStateModifier(state)))
            throw Exception("Can't modify " + (*it)->getNameWithState(), ErrorCodes::LOGICAL_ERROR);
    }
    void modifyPartState(const DataPartPtr & part, DataPartState state)