pgr_dijkstraVia
— Using dijkstra algorithm, it finds the route that goes through
a list of vertices.
Availability: 2.2.0
Given a list of vertices and a graph, this function is equivalent to finding the shortest path between \(vertex_i\) and \(vertex_{i+1}\) for all \(i < size\_of(vertex_via)\).
The paths represents the sections of the route.
Note
This is a proposed function
pgr_dijkstraVia(edges_sql, via_vertices)
pgr_dijkstraVia(edges_sql, via_vertices, directed, strict, U_turn_on_edge)
RETURNS SET OF (seq, path_pid, path_seq, start_vid, end_vid,
node, edge, cost, agg_cost, route_agg_cost) or EMPTY SET
pgr_dijkstraVia(edges_sql, via_vertices)
RETURNS SET OF (seq, path_pid, path_seq, start_vid, end_vid,
node, edge, cost, agg_cost, route_agg_cost) or EMPTY SET
Example:  Find the route that visits the vertices 1 3 9 in that order 

SELECT * FROM pgr_dijkstraVia(
'SELECT id, source, target, cost, reverse_cost FROM edge_table order by id',
ARRAY[1, 3, 9]
);
seq  path_id  path_seq  start_vid  end_vid  node  edge  cost  agg_cost  route_agg_cost
+++++++++
1  1  1  1  3  1  1  1  0  0
2  1  2  1  3  2  4  1  1  1
3  1  3  1  3  5  8  1  2  2
4  1  4  1  3  6  9  1  3  3
5  1  5  1  3  9  16  1  4  4
6  1  6  1  3  4  3  1  5  5
7  1  7  1  3  3  1  0  6  6
8  2  1  3  9  3  5  1  0  6
9  2  2  3  9  6  9  1  1  7
10  2  3  3  9  9  2  0  2  8
(10 rows)
pgr_dijkstraVia(edges_sql, via_vertices, directed, strict, U_turn_on_edge)
RETURNS SET OF (seq, path_pid, path_seq, start_vid, end_vid,
node, edge, cost, agg_cost, route_agg_cost) or EMPTY SET
Example:  Find the route that visits the vertices 1 3 9 in that order on an undirected graph, avoiding Uturns when possible 

SELECT * FROM pgr_dijkstraVia(
'SELECT id, source, target, cost, reverse_cost FROM edge_table order by id',
ARRAY[1, 3, 9], false, strict:=true, U_turn_on_edge:=false
);
seq  path_id  path_seq  start_vid  end_vid  node  edge  cost  agg_cost  route_agg_cost
+++++++++
1  1  1  1  3  1  1  1  0  0
2  1  2  1  3  2  2  1  1  1
3  1  3  1  3  3  1  0  2  2
4  2  1  3  9  3  5  1  0  2
5  2  2  3  9  6  9  1  1  3
6  2  3  3  9  9  2  0  2  4
(6 rows)
edges_sql:  an SQL query, which should return a set of rows with the following columns: 

Column  Type  Default  Description 

id  ANYINTEGER 
Identifier of the edge.  
source  ANYINTEGER 
Identifier of the first end point vertex of the edge.  
target  ANYINTEGER 
Identifier of the second end point vertex of the edge.  
cost  ANYNUMERICAL 
Weight of the edge (source, target)


reverse_cost  ANYNUMERICAL 
1  Weight of the edge (target, source),

Where:
ANYINTEGER:  SMALLINT, INTEGER, BIGINT 

ANYNUMERICAL:  SMALLINT, INTEGER, BIGINT, REAL, FLOAT 
Parameter  Type  Default  Description 

edges_sql  TEXT 
SQL query as described above.  
via_vertices  ARRAY[ANYINTEGER] 
Array of ordered vertices identifiers that are going to be visited.  
directed  BOOLEAN 
true 

strict  BOOLEAN 
false 

U_turn_on_edge  BOOLEAN 
true 

Parameter  Type  Description 

edges_sql  TEXT 
SQL query as described above. 
via_vertices  ARRAY[ANYINTEGER] 
Array of vertices identifiers 
directed  BOOLEAN 
(optional) Default is true (is directed). When set to false the graph is considered as Undirected 
strict  BOOLEAN 
(optional) ignores if a subsection of the route is missing and returns everything it found Default is true (is directed). When set to false the graph is considered as Undirected 
U_turn_on_edge  BOOLEAN 
(optional) Default is true (is directed). When set to false the graph is considered as Undirected 
Returns set of (start_vid, end_vid, agg_cost)
Column  Type  Description 

seq  BIGINT 
Sequential value starting from 1. 
path_pid  BIGINT 
Identifier of the path. 
path_seq  BIGINT 
Sequential value starting from 1 for the path. 
start_vid  BIGINT 
Identifier of the starting vertex of the path. 
end_vid  BIGINT 
Identifier of the ending vertex of the path. 
node  BIGINT 
Identifier of the node in the path from start_vid to end_vid. 
edge  BIGINT 
Identifier of the edge used to go from node to the next node in the path sequence. 1 for the last node of the path. 2 for the last node of the route. 
cost  FLOAT 
Cost to traverse from node using edge to the next node in the route sequence. 
agg_cost  FLOAT 
Total cost from start_vid to end_vid of the path. 
route_agg_cost  FLOAT 
Total cost from start_vid of path_pid = 1 to end_vid of the current path_pid . 
Example 1:  Find the route that visits the vertices 1 5 3 9 4 in that order 

SELECT * FROM pgr_dijkstraVia(
'SELECT id, source, target, cost, reverse_cost FROM edge_table order by id',
ARRAY[1, 5, 3, 9, 4]
);
seq  path_id  path_seq  start_vid  end_vid  node  edge  cost  agg_cost  route_agg_cost
+++++++++
1  1  1  1  5  1  1  1  0  0
2  1  2  1  5  2  4  1  1  1
3  1  3  1  5  5  1  0  2  2
4  2  1  5  3  5  8  1  0  2
5  2  2  5  3  6  9  1  1  3
6  2  3  5  3  9  16  1  2  4
7  2  4  5  3  4  3  1  3  5
8  2  5  5  3  3  1  0  4  6
9  3  1  3  9  3  5  1  0  6
10  3  2  3  9  6  9  1  1  7
11  3  3  3  9  9  1  0  2  8
12  4  1  9  4  9  16  1  0  8
13  4  2  9  4  4  2  0  1  9
(13 rows)
Example 2:  What’s the aggregate cost of the third path? 

SELECT agg_cost FROM pgr_dijkstraVia(
'SELECT id, source, target, cost, reverse_cost FROM edge_table order by id',
ARRAY[1, 5, 3, 9, 4]
)
WHERE path_id = 3 AND edge <0;
agg_cost

2
(1 row)
Example 3:  What’s the route’s aggregate cost of the route at the end of the third path? 

SELECT route_agg_cost FROM pgr_dijkstraVia(
'SELECT id, source, target, cost, reverse_cost FROM edge_table order by id',
ARRAY[1, 5, 3, 9, 4]
)
WHERE path_id = 3 AND edge < 0;
route_agg_cost

8
(1 row)
Example 4:  How are the nodes visited in the route? 

SELECT row_number() over () as node_seq, node
FROM pgr_dijkstraVia(
'SELECT id, source, target, cost, reverse_cost FROM edge_table order by id',
ARRAY[1, 5, 3, 9, 4]
)
WHERE edge <> 1 ORDER BY seq;
node_seq  node
+
1  1
2  2
3  5
4  6
5  9
6  4
7  3
8  6
9  9
10  4
(10 rows)
Example 5:  What are the aggregate costs of the route when the visited vertices are reached? 

SELECT path_id, route_agg_cost FROM pgr_dijkstraVia(
'SELECT id, source, target, cost, reverse_cost FROM edge_table order by id',
ARRAY[1, 5, 3, 9, 4]
)
WHERE edge < 0;
path_id  route_agg_cost
+
1  2
2  6
3  8
4  9
(4 rows)
Example 6:  show the route’s seq and aggregate cost and a status of “passes in front” or “visits” node 9 

SELECT seq, route_agg_cost, node, agg_cost ,
CASE WHEN edge = 1 THEN 'visits'
ELSE 'passes in front'
END as status
FROM pgr_dijkstraVia(
'SELECT id, source, target, cost, reverse_cost FROM edge_table order by id',
ARRAY[1, 5, 3, 9, 4])
WHERE node = 9 and (agg_cost <> 0 or seq = 1);
seq  route_agg_cost  node  agg_cost  status
++++
6  4  9  2  passes in front
11  8  9  2  visits
(2 rows)
ROLLBACK;
ROLLBACK
Indices and tables