**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 :)

added_filter_nodes.nodes.push_back(&before_where->findInOutputs(where_column_name));
    bool can_use_aggregate_projection = true;
    /
    /
    if (analysis_result.join != nullptr || analysis_result.array_join != nullptr)
        can_use_aggregate_projection = false;
    /
    /
    /
    /
    /
    /
    /
    /
    std::vector<ProjectionCandidate> candidates;
    NameSet keys;
    std::unordered_map<std::string_view, size_t> key_name_pos_map;
    size_t pos = 0;
    for (const auto & desc : select.getQueryAnalyzer()->aggregationKeys())
    {
        keys.insert(desc.name);
        key_name_pos_map.insert({desc.name, pos++});
    }
    auto actions_settings = ExpressionActionsSettings::fromSettings(settings, CompileExpressions::yes);
    /
    /
    /
    auto rewrite_before_where =
        [&](ProjectionCandidate & candidate, const ProjectionDescription & projection,
            NameSet & required_columns, const Block & source_block, const Block & aggregates)