**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 auto & partition_key = metadata_snapshot->getPartitionKey();
            auto minmax_columns_names = getMinMaxColumnsNames(partition_key);
            minmax_columns_types = getMinMaxColumnsTypes(partition_key);
            minmax_idx_condition.emplace(
                query_info, query_context, minmax_columns_names,
                getMinMaxExpr(partition_key, ExpressionActionsSettings::fromContext(query_context)));
            partition_pruner.emplace(metadata_snapshot, query_info, query_context, false );
        }
        
        ASTPtr expression_ast;
        VirtualColumnUtils::prepareFilterBlockWithQuery(query_info.query, query_context, virtual_columns_block, expression_ast);
        if (expression_ast)
            VirtualColumnUtils::filterBlockWithQuery(query_info.query, virtual_columns_block, query_context, expression_ast);
        rows = virtual_columns_block.rows();
        part_name_column = virtual_columns_block.getByName("_part").column;
    }
    auto filter_column = ColumnUInt8::create();
    auto & filter_column_data = filter_column->getData();
    DataPartsVector real_parts;
    real_parts.reserve(rows);
    for (size_t row = 0, part_idx = 0; row < rows; ++row, ++part_idx)
    {
        if (part_name_column)
        {
            while (parts[part_idx]->name != part_name_column->getDataAt(row))
                ++part_idx;
        }
        const auto & part = parts[part_idx];
        if (part->isEmpty())
            continue;