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
else if (to_remove == RemoveProperty::COMMENT)
            {
                column.comment = String{};
            }
            else if (to_remove == RemoveProperty::TTL)
            {
                column.ttl.reset();
            }
            else
            {
                if (codec)
                    column.codec = CompressionCodecFactory::instance().validateCodecAndGetPreprocessedAST(codec, data_type ? data_type : column.type, false, true);
                if (comment)
                    column.comment = *comment;
                if (ttl)
                    column.ttl = ttl;
                if (data_type)
                    column.type = data_type;
                
                
                if (default_expression || data_type)
                {
                    column.default_desc.kind = default_kind;
                    column.default_desc.expression = default_expression;
                }
            }
        });
    }
    else if (type == MODIFY_ORDER_BY)
    {