how to get the distance of sequence of nodes in pgr_dijkstra pgrouting?

I have an array of integers(nodes or destinations) i.e array[2,3,4,5,6,8] that need to be visited in the given sequence. What I want is, to get the shortest distance using pgr_dijkstra. But the pgr_dijkstra finds the shortest path for two points, therefore I need to find the distance of each pair using pgr_dijkstra and adding all distances to get the total distance. The pairs will be like
2,3
3,4

4,5

5,6

6,8. Is there any way to define a function that takes this array and finds the shortest path using pgr_dijkstra.

Query is: for 1st pair(2,3) SELECT * FROM pgr_dijkstra('SELECT gid as id,source, target, rcost_len AS cost FROM finalroads',2,3, false);

for 2nd pair(3,4) SELECT * FROM pgr_dijkstra('SELECT gid as id,source, target, rcost_len AS cost FROM finalroads'***,3,4,*** false)

for 3rd pair(4,5) SELECT * FROM pgr_dijkstra('SELECT gid as id,source, target, rcost_len AS cost FROM finalroads'***,4,5,*** false);

NOTE: The array size is not fixed, it can be different.

Is there any way to automate this in postgres sql may be using a loop etc? Please let me know how to do it. Thank you.

Using the solution provided in this post that makes use of a source table, it is possible to use your array. Note that the orig is your array omitting the last entry, and the dest omits the 1st entry.

SELECT 
  source, 
  target,
  (SELECT SUM(cost) FROM  -- or whatever you want to do with the routing result
     (SELECT * 
      FROM pgr_dijkstra('SELECT gid as id,source, target, rcost_len AS cost FROM finalroads',
                        orig,
                        dest, 
                        false))
     ) AS foo 
  ) AS cost
FROM (
  select unnest(myarray[:array_upper(myarray,1)-1])  as orig,
         unnest(myarray[2:]) as dest 
  from (select array[1,2,3,4] myarray) b) c;