pgr_dagShortestPath
— Returns the shortest path(s) for weighted directed acyclic graphs(DAG).
In particular, the DAG shortest paths algorithm implemented by Boost.Graph.
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Possible server crash
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Experimental functions
Availability
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Shortest Path for Directed Acyclic Graph(DAG) is a graph search algorithm that solves the shortest path problem for
weighted directed acyclic graph, producing a shortest path from
a starting vertex (start_vid
) to an ending vertex (end_vid
).
This implementation can only be used with a directed graph with no cycles i.e. directed acyclic graph.
The algorithm relies on topological sorting the dag to impose a linear ordering on the vertices, and thus is more efficient for DAG’s than either the Dijkstra or BellmanFord algorithm.
Summary
pgr_dagShortestPath(edges_sql, from_vid, to_vid)
pgr_dagShortestPath(edges_sql, from_vid, to_vids)
pgr_dagShortestPath(edges_sql, from_vids, to_vid)
pgr_dagShortestPath(edges_sql, from_vids, to_vids)
RETURNS SET OF (seq, path_seq, node, edge, cost, agg_cost)
OR EMPTY SET
pgr_dagShortestPath(edges_sql, from_vid, to_vid)
RETURNS SET OF (seq, path_seq, node, edge, cost, agg_cost)
OR EMPTY SET
Example:  From vertex \(1\) to vertex \(6\) 

SELECT * FROM pgr_dagShortestPath(
'SELECT id, source, target, cost FROM edge_table',
1, 6
);
seq  path_seq  node  edge  cost  agg_cost
+++++
1  1  1  1  1  0
2  2  2  4  1  1
3  3  5  8  1  2
4  4  6  1  0  3
(4 rows)
pgr_dagShortestPath(edges_sql, from_vid, to_vids)
RETURNS SET OF (seq, path_seq, node, edge, cost, agg_cost)
OR EMPTY SET
Example:  From vertex \(1\) to vertices \(\{ 5, 6\}\) 

SELECT * FROM pgr_dagShortestPath(
'SELECT id, source, target, cost FROM edge_table',
1, ARRAY[5,6]
);
seq  path_seq  node  edge  cost  agg_cost
+++++
1  1  1  1  1  0
2  2  2  4  1  1
3  3  5  1  0  2
4  1  1  1  1  0
5  2  2  4  1  1
6  3  5  8  1  2
7  4  6  1  0  3
(7 rows)
pgr_dagShortestPath(edges_sql, from_vids, to_vid)
RETURNS SET OF (seq, path_seq, node, edge, cost, agg_cost)
OR EMPTY SET
Example:  From vertices \(\{1, 3\}\) to vertex \(6\) 

SELECT * FROM pgr_dagShortestPath(
'SELECT id, source, target, cost FROM edge_table',
ARRAY[1,3], 6
);
seq  path_seq  node  edge  cost  agg_cost
+++++
1  1  1  1  1  0
2  2  2  4  1  1
3  3  5  8  1  2
4  4  6  1  0  3
5  1  3  5  1  0
6  2  6  1  0  1
(6 rows)
pgr_dagShortestPath(edges_sql, from_vids, to_vids)
RETURNS SET OF (seq, path_seq, node, edge, cost, agg_cost)
OR EMPTY SET
Example:  From vertices \(\{1, 4\}\) to vertices \(\{12, 6\}\) 

SELECT * FROM pgr_dagShortestPath(
'SELECT id, source, target, cost FROM edge_table',
ARRAY[1, 4],ARRAY[12,6]
);
seq  path_seq  node  edge  cost  agg_cost
+++++
1  1  1  1  1  0
2  2  2  4  1  1
3  3  5  8  1  2
4  4  6  1  0  3
5  1  1  1  1  0
6  2  2  4  1  1
7  3  5  10  1  2
8  4  10  12  1  3
9  5  11  13  1  4
10  6  12  1  0  5
11  1  4  16  1  0
12  2  9  15  1  1
13  3  12  1  0  2
(13 rows)
Description of the parameters of the signatures
Parameter  Type  Default  Description 

edges_sql  TEXT 
SQL query as described above.  
start_vid  BIGINT 
Identifier of the starting vertex of the path.  
start_vids  ARRAY[BIGINT] 
Array of identifiers of starting vertices.  
end_vid  BIGINT 
Identifier of the ending vertex of the path.  
end_vids  ARRAY[BIGINT] 
Array of identifiers of ending vertices. 
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 
Returns set of (seq, path_seq [, start_vid] [, end_vid], node, edge, cost, agg_cost)
Column  Type  Description 

seq  INT 
Sequential value starting from 1. 
path_seq  INT 
Relative position in the path. Has value 1 for the beginning of a path. 
start_vid  BIGINT 
Identifier of the starting vertex. Returned when multiple starting vetrices are in the query. 
end_vid  BIGINT 
Identifier of the ending vertex. Returned when multiple ending vertices are in the query. 
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. 
cost  FLOAT 
Cost to traverse from node using edge to the next node in the path sequence. 
agg_cost  FLOAT 
Aggregate cost from start_v to node . 
Indices and tables