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 (comment)
            column.comment = *comment;
        if (codec)
            column.codec = CompressionCodecFactory::instance().validateCodecAndGetPreprocessedAST(codec, data_type, false, true);
        column.ttl = ttl;
        metadata.columns.add(column, after_column, first);
        
        if (context->getSettingsRef().flatten_nested)
            metadata.columns.flattenNested();
    }
    else if (type == DROP_COLUMN)
    {
        
        if (!clear && !partition)
            metadata.columns.remove(column_name);
    }
    else if (type == MODIFY_COLUMN)
    {
        metadata.columns.modify(column_name, after_column, first, [&](ColumnDescription & column)
        {
            if (to_remove == RemoveProperty::DEFAULT
                || to_remove == RemoveProperty::MATERIALIZED
                || to_remove == RemoveProperty::ALIAS)
            {
                column.default_desc = ColumnDefault{};
            }
            else if (to_remove == RemoveProperty::CODEC)
            {
                column.codec.reset();
            }