**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 :)

}
            break;
            case PartitionCommand::REPLACE_PARTITION:
            {
                if (command.replace)
                    checkPartitionCanBeDropped(command.partition, query_context);
                String from_database = query_context->resolveDatabase(command.from_database);
                auto from_storage = DatabaseCatalog::instance().getTable({from_database, command.from_table}, query_context);
                replacePartitionFrom(from_storage, command.partition, command.replace, query_context);
            }
            break;
            case PartitionCommand::FETCH_PARTITION:
                fetchPartition(command.partition, metadata_snapshot, command.from_zookeeper_path, command.part, query_context);
                break;
            case PartitionCommand::FREEZE_PARTITION:
            {
                auto lock = lockForShare(query_context->getCurrentQueryId(), query_context->getSettingsRef().lock_acquire_timeout);
                current_command_results = freezePartition(command.partition, metadata_snapshot, command.with_name, query_context, lock);
            }
            break;
            case PartitionCommand::FREEZE_ALL_PARTITIONS:
            {
                auto lock = lockForShare(query_context->getCurrentQueryId(), query_context->getSettingsRef().lock_acquire_timeout);
                current_command_results = freezeAll(command.with_name, metadata_snapshot, query_context, lock);
            }
            break;
            case PartitionCommand::UNFREEZE_PARTITION:
            {
                auto lock = lockForShare(query_context->getCurrentQueryId(), query_context->getSettingsRef().lock_acquire_timeout);
                current_command_results = unfreezePartition(command.partition, command.with_name, query_context, lock);