22.2.1.4422.

```
create table test_alias (K Int64, D Date, S String, B Int64 Alias length(S)) Engine=MergeTree order by K;
insert into test_alias select number, today(), 'sdfsdfsdfsdfsdfds' from numbers(10000000);

session1: 
clickhouse-benchmark -c 10 <<< "insert into test_alias select number, today(), 'sdfsdfsdfsdfsdfds' from numbers(10000)"

session2: 
alter table test_alias drop column B;
0 rows in set. Elapsed: 251.043 sec.
```

especially it can be a problem with S3 disks

Alias columns do not persist in parts even in columns.txt
result.partition = partition;
        result.predicate = nullptr;
    }
    else if (type == DROP_PROJECTION)
    {
        result.type = MutationCommand::Type::DROP_PROJECTION;
        result.column_name = projection_name;
        if (clear)
            result.clear = true;
        if (partition)
            result.partition = partition;
        result.predicate = nullptr;
    }
    else if (type == RENAME_COLUMN)
    {
        result.type = MutationCommand::Type::RENAME_COLUMN;
        result.column_name = column_name;
        result.rename_to = rename_to;
    }
    result.ast = ast->clone();
    apply(metadata, context);
    return result;
}
void AlterCommands::apply(StorageInMemoryMetadata & metadata, ContextPtr context) const
{
    if (!prepared)
        throw DB::Exception("Alter commands is not prepared. Cannot apply. It's a bug", ErrorCodes::LOGICAL_ERROR);
    auto metadata_copy = metadata;
    for (const AlterCommand & command : *this)
        if (!command.ignore)