Я не вижу никакого простого ответа, охватывающего часть «PARTITION BY», поэтому вот мой:
SELECT
*
FROM (
select
CASE WHEN @partitionBy_1 = l THEN @row_number:=@row_number+1 ELSE @row_number:=1 END AS i
, @partitionBy_1:=l AS p
, t.*
from (
select @row_number:=0,@partitionBy_1:=null
) as x
cross join (
select 1 as n, 'a' as l
union all
select 1 as n, 'b' as l
union all
select 2 as n, 'b' as l
union all
select 2 as n, 'a' as l
union all
select 3 as n, 'a' as l
union all
select 3 as n, 'b' as l
) as t
ORDER BY l, n
) AS X
where i > 1
CASE WHEN @partitionBy_1 = part1 AND @partitionBy_2 = part2 [...] THEN @row_number:=@row_number+1 ELSE @row_number:=1 END AS i
, @partitionBy_1:=part1 AS P1
, @partitionBy_2:=part2 AS P2
[...]
FROM (
SELECT @row_number:=0,@partitionBy_1:=null,@partitionBy_2:=null[...]
) as x