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.
{
        const Container & bitmap = maps[bitmap_number]->bitmap;
        IColumn::Filter filter(bitmap.size());
        for (size_t i = 0; i < bitmap.size(); ++i)
            filter[i] = !bitmap[i];
        return filter;
    }
private:
    std::vector<std::unique_ptr<Bitmap>> maps;
};
struct MergeJoinEqualRange
{
    size_t left_start = 0;
    size_t right_start = 0;
    size_t left_length = 0;
    size_t right_length = 0;
    bool empty() const { return !left_length && !right_length; }
};
using Range = MergeJoinEqualRange;
class MergeJoinCursor
{
public:
    MergeJoinCursor(const Block & block, const SortDescription & desc_)
        : impl(SortCursorImpl(block, desc_))
    {
        
        if (impl.permutation)
            throw Exception("Logical error: MergeJoinCursor doesn't support permutation", ErrorCodes::LOGICAL_ERROR);
    }
    size_t position() const { return impl.getRow(); }