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
command.apply(metadata_copy, context);
    
    metadata_copy.sorting_key.recalculateWithNewAST(metadata_copy.sorting_key.definition_ast, metadata_copy.columns, context);
    if (metadata_copy.primary_key.definition_ast != nullptr)
    {
        metadata_copy.primary_key.recalculateWithNewAST(metadata_copy.primary_key.definition_ast, metadata_copy.columns, context);
    }
    else
    {
        metadata_copy.primary_key = KeyDescription::getKeyFromAST(metadata_copy.sorting_key.definition_ast, metadata_copy.columns, context);
        metadata_copy.primary_key.definition_ast = nullptr;
    }
    
    if (metadata_copy.partition_key.definition_ast != nullptr)
        metadata_copy.partition_key.recalculateWithNewAST(metadata_copy.partition_key.definition_ast, metadata_copy.columns, context);
    
    if (metadata_copy.sampling_key.definition_ast != nullptr)
        metadata_copy.sampling_key.recalculateWithNewAST(metadata_copy.sampling_key.definition_ast, metadata_copy.columns, context);
    
    for (auto & index : metadata_copy.secondary_indices)
    {
        try
        {
            index = IndexDescription::getIndexFromAST(index.definition_ast, metadata_copy.columns, context);
        }
        catch (Exception & exception)
        {
            exception.addMessage("Cannot apply mutation because it breaks skip index " + index.name);
            throw;
        }