**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 :)

Block getMinMaxCountProjectionBlock(
        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;
    std::optional<ProjectionCandidate> getQueryProcessingStageWithAggregateProjection(
        ContextPtr query_context, const StorageSnapshotPtr & storage_snapshot, SelectQueryInfo & query_info) const;
    QueryProcessingStage::Enum getQueryProcessingStage(
        ContextPtr query_context,
        QueryProcessingStage::Enum to_stage,
        const StorageSnapshotPtr & storage_snapshot,
        SelectQueryInfo & info) const override;
    ReservationPtr reserveSpace(UInt64 expected_size, VolumePtr & volume) const;
    static ReservationPtr tryReserveSpace(UInt64 expected_size, const DataPartStoragePtr & data_part_storage);
    static ReservationPtr reserveSpace(UInt64 expected_size, const DataPartStoragePtr & data_part_storage);
    static ReservationPtr reserveSpace(UInt64 expected_size, const DataPartStorageBuilderPtr & data_part_storage_builder);
    static bool partsContainSameProjections(const DataPartPtr & left, const DataPartPtr & right);
    StoragePolicyPtr getStoragePolicy() const override;
    bool supportsPrewhere() const override { return true; }
    bool supportsFinal() const override;
    bool supportsSubcolumns() const override { return true; }
    bool supportsTTL() const override { return true; }
    bool supportsDynamicSubcolumns() const override { return true; }