with
  w_data as
  (
    select 1  as fk_id, 1  as fn_order, 'KEY_1' as fv_grp from dual union all
    select 2  as fk_id, 2  as fn_order, 'KEY_1' as fv_grp from dual union all
    select 3  as fk_id, 3  as fn_order, 'KEY_1' as fv_grp from dual union all
    select 4  as fk_id, 4  as fn_order, 'KEY_2' as fv_grp from dual union all
    select 5  as fk_id, 5  as fn_order, 'KEY_2' as fv_grp from dual union all
    select 6  as fk_id, 6  as fn_order, 'KEY_1' as fv_grp from dual union all
    select 7  as fk_id, 7  as fn_order, 'KEY_3' as fv_grp from dual union all
    select 8  as fk_id, 8  as fn_order, 'KEY_3' as fv_grp from dual union all
    select 9  as fk_id, 9  as fn_order, 'KEY_3' as fv_grp from dual union all
    select 10 as fk_id, 10 as fn_order, 'KEY_4' as fv_grp from dual
  )
select *
  from w_data match_recognize(
                order by fn_order
                measures --strt.fk_id as fk_id,
                         --strt.fv_grp as fv_grp,
                         match_number() as match_num,
                         classifier()   as clsf
                --one row per match
                all rows per match
                after match skip to last neq
                pattern (strt neq eq*)
                define eq  as eq.fv_grp   = prev(eq.fv_grp),
                       neq as neq.fv_grp != prev(neq.fv_grp)
              )
order by fk_id

FN_ORDER	MATCH_NUM	CLSF	FK_ID	FV_GRP
3	1	STRT	3	KEY_1
4	1	NEQ	4	KEY_2
5	1	EQ	5	KEY_2
5	2	STRT	5	KEY_2
6	2	NEQ	6	KEY_1
6	3	STRT	6	KEY_1
7	3	NEQ	7	KEY_3
8	3	EQ	8	KEY_3
9	3	EQ	9	KEY_3
9	4	STRT	9	KEY_3
10	4	NEQ	10	KEY_4

CLSF	FK_ID	FV_GRP
NEQ		1	KEY_1
EQ		2	KEY_1
EQ		3	KEY_1
NEQ		4	KEY_2
EQ		5	KEY_2
NEQ		6	KEY_1
NEQ		7	KEY_3
EQ		8	KEY_3
EQ		9	KEY_3
NEQ		10	KEY_4