drop table testobject6;

create table testobject6(
	pk1 int8,
	pk2 int8,
	pk3 int8,
	pk4 int8,
	pk5 int8,
	PRIMARY KEY(pk1, pk2, pk3, pk4, pk5)
);

insert into testobject6 
	(pk1, pk2, pk3, pk4, pk5) 
values 
	(1,2,3,4,5),
	(3,1,4,0,7),
	(2,9,5,5,6),
	(1,8,8,5,7),
	(1,9,0,0,8);

select * from testobject6;

select * 
  from testobject6
 where ... ??? -- допустим следующую за (2,9,5,5,6)
 limit 1;

select t.lead_pk1
	,t.lead_pk2
	,t.lead_pk3
	,t.lead_pk4
	,t.lead_pk5
  from (
    select 
		pk1, pk2, pk3, pk4, pk5
		,LEAD (pk1,1) OVER (ORDER BY pk1, pk2, pk3, pk4, pk5) lead_pk1
		,LEAD (pk2,1) OVER (ORDER BY pk1, pk2, pk3, pk4, pk5) lead_pk2
		,LEAD (pk3,1) OVER (ORDER BY pk1, pk2, pk3, pk4, pk5) lead_pk3
		,LEAD (pk4,1) OVER (ORDER BY pk1, pk2, pk3, pk4, pk5) lead_pk4
		,LEAD (pk5,1) OVER (ORDER BY pk1, pk2, pk3, pk4, pk5) lead_pk5
	  from testobject6
  ) t
 where t.pk1 = 1 and t.pk2 = 2 and t.pk3 = 3 and t.pk4 = 4 and t.pk5 = 5
;

select pk1, pk2, pk3, pk4, pk5
  from testobject6
 where pk1::text || pk2::text || pk3::text || pk4::text || pk5::text > '12345'
 order by pk1, pk2, pk3, pk4, pk5
 limit 1;

select pk1, pk2, pk3, pk4, pk5
  from testobject6
 where pk1::text || '/' || pk2::text || '/' || pk3::text || '/' || pk4::text || '/' || pk5::text > '1/2/3/4/5'
 order by pk1, pk2, pk3, pk4, pk5
 limit 1;

select *
  from (
         select * 
           from t
           -- t.pk1 = 1 and t.pk2 = 2 and t.pk3 = 3 and t.pk4 = 4 and t.pk5 = 5  -- так не сработает
          order by ....
          limit 2
       ) v
 order by ...
 limit 1 offset 1
 
 

SELECT * 
FROM testobject6
WHERE (pk1, pk2, pk3, pk4, pk5) > (2,9,5,5,6)
ORDER BY pk1, pk2, pk3, pk4, pk5
LIMIT 1;