**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 :)

{
    auto res = getDataPartsVectorForInternalUsage({DataPartState::Active, DataPartState::Outdated});
    filterVisibleDataParts(res, snapshot_version, current_tid);
    return res;
}
void MergeTreeData::filterVisibleDataParts(DataPartsVector & maybe_visible_parts, CSN snapshot_version, TransactionID current_tid) const
{
    [[maybe_unused]] size_t total_size = maybe_visible_parts.size();
    auto need_remove_pred = [snapshot_version, &current_tid] (const DataPartPtr & part) -> bool
    {
        return !part->version.isVisible(snapshot_version, current_tid);
    };
    std::erase_if(maybe_visible_parts, need_remove_pred);
    [[maybe_unused]] size_t visible_size = maybe_visible_parts.size();
    auto get_part_names = [&maybe_visible_parts]() -> Strings
    {
        Strings visible_part_names;
        for (const auto & p : maybe_visible_parts)
            visible_part_names.push_back(p->name);
        return visible_part_names;
    };
    LOG_TEST(log, "Got {} parts (of {}) visible in snapshot {} (TID {}): {}",
             visible_size, total_size, snapshot_version, current_tid, fmt::join(get_part_names(), ", "));
}
std::unordered_set<String> MergeTreeData::getPartitionIDsFromQuery(const ASTs & asts, ContextPtr local_context) const