**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 StorageMetadataPtr & metadata_snapshot,
    const Names & required_columns,
    bool has_filter,
    const SelectQueryInfo & query_info,
    const DataPartsVector & parts,
    DataPartsVector & normal_parts,
    const PartitionIdToMaxBlock * max_block_numbers_to_read,
    ContextPtr query_context) const
{
    if (!metadata_snapshot->minmax_count_projection)
        throw Exception(
            "Cannot find the definition of minmax_count projection but it's used in current query. It's a bug",
            ErrorCodes::LOGICAL_ERROR);
    auto block = metadata_snapshot->minmax_count_projection->sample_block.cloneEmpty();
    bool need_primary_key_max_column = false;
    const auto & primary_key_max_column_name = metadata_snapshot->minmax_count_projection->primary_key_max_column_name;
    NameSet required_columns_set(required_columns.begin(), required_columns.end());
    if (!primary_key_max_column_name.empty())
        need_primary_key_max_column = required_columns_set.contains(primary_key_max_column_name);
    auto partition_minmax_count_columns = block.mutateColumns();
    auto partition_minmax_count_column_names = block.getNames();
    auto insert = [](ColumnAggregateFunction & column, const Field & value)
    {
        auto func = column.getAggregateFunction();
        Arena & arena = column.createOrGetArena();
        size_t size_of_state = func->sizeOfData();
        size_t align_of_state = func->alignOfData();