```sql
drop table if exists src;

create table src( A Int64, B String, C String) Engine=MergeTree order by A
SETTINGS min_bytes_for_wide_part=0;
insert into src values(1, 'one', 'test');

alter table src detach partition tuple();

alter table src modify column B Nullable(String);

alter table src attach partition tuple();
select * from src;
┌─A─┬─B───┬─C────┐
│ 1 │ one │ test │
└───┴─────┴──────┘

alter table src update C = 'test1' where 1 settings mutations_sync=2;

select * from src;
┌─A─┬─B────┬─C─────┐
│ 1 │ ᴺᵁᴸᴸ │ test1 │   -- expected B='one'
└───┴──────┴───────┘
```

```sql
drop table if exists src;
create table src( A String, B String, C String) Engine=MergeTree order by A
SETTINGS min_bytes_for_wide_part=0;
insert into src values('one', 'one', 'test');

alter table src detach partition tuple();

alter table src modify column A LowCardinality(String);

alter table src attach partition tuple();

select * from src;
┌─A───┬─B───┬─C────┐
│ one │ one │ test │
└─────┴─────┴──────┘

alter table src update C = 'test1' where 1 settings mutations_sync=2;

select * from src;

Received exception from server (version 22.9.1):
Code: 49. DB::Exception: Received from localhost:9000. DB::Exception: 
Got empty stream for SerializationLowCardinality keys.: (while reading column A): 
(while reading from part /var/lib/clickhouse/store/11b/11b74812-48b9-4c1f-9bdc-3e7a28137a9e/all_3_3_0_4/ from mark 0 with max_rows_to_read = 1): 
While executing MergeTreeInOrder. (LOGICAL_ERROR)

```

```sql
drop table if exists src;
create table src( A String, B String, C String) Engine=MergeTree order by A
SETTINGS min_bytes_for_wide_part=0;
insert into src values('one', 'one', 'test');

alter table src detach partition tuple();

alter table src modify column A LowCardinality(String);

alter table src attach partition tuple();

select * from src;
┌─A───┬─B───┬─C────┐
│ one │ one │ test │
└─────┴─────┴──────┘

alter table src modify column C LowCardinality(String);

select * from src;

Received exception from server (version 22.9.3):
Code: 49. DB::Exception: Received from localhost:9000. 
DB::Exception: Got empty stream for SerializationLowCardinality keys.: 
```

related https://github.com/ClickHouse/ClickHouse/issues/42083 , https://github.com/ClickHouse/ClickHouse/issues/42074
(basically it's the same one issue, but I opened this one, because I think the root issue is in `alter update`.

it seems `alter update` updates columns.txt for all columns even if they are not participated in the `alter update`.
FutureMergedMutatedPartPtr future_part_,
    StorageMetadataPtr metadata_snapshot_,
    MutationCommandsConstPtr commands_,
    MergeListEntry * mutate_entry_,
    time_t time_of_mutation_,
    ContextPtr context_,
    ReservationSharedPtr space_reservation_,
    TableLockHolder & table_lock_holder_,
    const MergeTreeTransactionPtr & txn,
    MergeTreeData & data_,
    MergeTreeDataMergerMutator & mutator_,
    ActionBlocker & merges_blocker_)
    : ctx(std::make_shared<MutationContext>())
{
    ctx->data = &data_;
    ctx->mutator = &mutator_;
    ctx->merges_blocker = &merges_blocker_;
    ctx->holder = &table_lock_holder_;
    ctx->mutate_entry = mutate_entry_;
    ctx->commands = commands_;
    ctx->context = context_;
    ctx->time_of_mutation = time_of_mutation_;
    ctx->future_part = future_part_;
    ctx->metadata_snapshot = metadata_snapshot_;
    ctx->space_reservation = space_reservation_;