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 (type == COMMENT_COLUMN || type == COMMENT_TABLE)
    {
        return true;
    }
    else if (type == MODIFY_COLUMN)
    {
        return comment.has_value()
            && codec == nullptr
            && data_type == nullptr
            && default_expression == nullptr
            && ttl == nullptr;
    }
    return false;
}
bool AlterCommand::isTTLAlter(const StorageInMemoryMetadata & metadata) const