**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 :)

{
    if (new_partition_key.expression_list_ast->children.empty())
        return;
    checkKeyExpression(*new_partition_key.expression, new_partition_key.sample_block, "Partition", allow_nullable_key);
    
    DataTypes minmax_idx_columns_types = getMinMaxColumnsTypes(new_partition_key);
    
    
    bool has_date_column = false;
    bool has_datetime_column = false;
    for (size_t i = 0; i < minmax_idx_columns_types.size(); ++i)
    {
        if (isDate(minmax_idx_columns_types[i]))
        {
            if (!has_date_column)
            {
                minmax_idx_date_column_pos = i;
                has_date_column = true;
            }
            else
            {
                
                minmax_idx_date_column_pos = -1;
            }
        }
    }
    if (!has_date_column)
    {
        for (size_t i = 0; i < minmax_idx_columns_types.size(); ++i)