**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 :)

throw Exception(
                        "Projection with name " + backQuote(projection.name) + " already exists",
                        ErrorCodes::LOGICAL_ERROR);
            projections_names.insert(projection.name);
        }
    }
    checkKeyExpression(*new_sorting_key.expression, new_sorting_key.sample_block, "Sorting", allow_nullable_key);
}
void MergeTreeData::setProperties(const StorageInMemoryMetadata & new_metadata, const StorageInMemoryMetadata & old_metadata, bool attach)
{
    checkProperties(new_metadata, old_metadata, attach);
    setInMemoryMetadata(new_metadata);
}
namespace
{
ExpressionActionsPtr getCombinedIndicesExpression(
    const KeyDescription & key,
    const IndicesDescription & indices,
    const ColumnsDescription & columns,
    ContextPtr context)
{
    ASTPtr combined_expr_list = key.expression_list_ast->clone();
    for (const auto & index : indices)
        for (const auto & index_expr : index.expression_list_ast->children)
            combined_expr_list->children.push_back(index_expr->clone());
    auto syntax_result = TreeRewriter(context).analyze(combined_expr_list, columns.getAllPhysical());
    return ExpressionAnalyzer(combined_expr_list, syntax_result, context).getActions(false);
}
}
ExpressionActionsPtr MergeTreeData::getMinMaxExpr(const KeyDescription & partition_key, const ExpressionActionsSettings & settings)