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
{
        if (from->equals(*to))
            return true;
        auto it_range = ALLOWED_CONVERSIONS.equal_range(typeid(*from));
        for (auto it = it_range.first; it != it_range.second; ++it)
        {
            if (it->second == typeid(*to))
                return true;
        }
        const auto * arr_from = typeid_cast<const DataTypeArray *>(from);
        const auto * arr_to = typeid_cast<const DataTypeArray *>(to);
        if (arr_from && arr_to)
        {
            from = arr_from->getNestedType().get();
            to = arr_to->getNestedType().get();
            continue;
        }
        const auto * nullable_from = typeid_cast<const DataTypeNullable *>(from);
        const auto * nullable_to = typeid_cast<const DataTypeNullable *>(to);
        if (nullable_to)
        {
            from = nullable_from ? nullable_from->getNestedType().get() : from;
            to = nullable_to->getNestedType().get();
            continue;
        }
        return false;
    }
}
}
bool AlterCommand::isSettingsAlter() const