**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 :)

max_added_blocks);
            if (!normal_result_ptr->error())
            {
                selected_candidate = &*minmax_count_projection_candidate;
                selected_candidate->merge_tree_normal_select_result_ptr = normal_result_ptr;
                min_sum_marks = query_info.minmax_count_projection_block.rows() + normal_result_ptr->marks();
            }
        }
    };
    /
    if (minmax_count_projection_candidate)
        prepare_min_max_count_projection();
    /
    if (!selected_candidate || !selected_candidate->complete)
        for (const auto & projection : metadata_snapshot->projections)
            add_projection_candidate(projection);
    /
    if (!candidates.empty())
    {
        query_info.merge_tree_select_result_ptr = reader.estimateNumMarksToRead(
            parts,
            analysis_result.required_columns,
            metadata_snapshot,
            metadata_snapshot,
            query_info,
            added_filter_nodes,
            query_context,
            settings.max_threads,
            max_added_blocks);
        if (!query_info.merge_tree_select_result_ptr->error())