Thankfully "partial merge join" is disabled by default.

```
milovidov-desktop :) SET max_block_size = 6, join_algorithm = 'partial_merge'

SET max_block_size = 6, join_algorithm = 'partial_merge'

Query id: 600704b7-b455-4726-8a9c-8e45b509f2fb

Ok.

0 rows in set. Elapsed: 0.002 sec. 

milovidov-desktop :) SELECT blockSize() bs FROM (SELECT 1 s) js1 ALL RIGHT JOIN (SELECT arrayJoin([2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3]) s) js2 USING (s) GROUP BY bs ORDER BY bs;

SELECT blockSize() AS bs
FROM
(
    SELECT 1 AS s
) AS js1
ALL RIGHT JOIN
(
    SELECT arrayJoin([2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3]) AS s
) AS js2 USING (s)
GROUP BY bs
ORDER BY bs ASC

Query id: ae51c589-4b69-4e90-a3a9-7ef4ead72af9

→ Progress: 2.00 rows, 2.00 B (18.21 rows/s., 18.21 B/s.)
```

Found by stress test.
{
public:
    NonMergeJoinedBlockInputStream(const MergeJoin & parent_, const Block & result_sample_block_, UInt64 max_block_size_)
        : NotJoined(*parent_.table_join,
                    parent_.modifyRightBlock(parent_.right_sample_block),
                    parent_.right_sample_block,
                    result_sample_block_)
        , parent(parent_)
        , max_block_size(max_block_size_)
    {}
    String getName() const override { return "NonMergeJoined"; }
    Block getHeader() const override { return result_sample_block; }
protected:
    Block readImpl() override