pgr_apspWarshall - All Pairs Shortest Path, Floyd-Warshall Algorithm

Name

pgr_apspWarshall - Returns all costs for each pair of nodes in the graph.

Synopsis

The Floyd-Warshall algorithm (also known as Floyd’s algorithm and other names) is a graph analysis algorithm for finding the shortest paths between all pairs of nodes in a weighted graph. Returns a set of pgr_costResult (seq, id1, id2, cost) rows for every pair of nodes in the graph.

pgr_costResult[] pgr_apspWarshall(sql text, directed boolean, reverse_cost boolean);

Description

sql:

a SQL query that should return the edges for the graph that will be analyzed:

SELECT id, source, target, cost FROM edge_table;
id:int4 identifier of the edge
source:int4 identifier of the source vertex for this edge
target:int4 identifier of the target vertex for this edge
cost:float8 a positive value for the cost to traverse this edge
directed:

true if the graph is directed
reverse_cost:

if true, the reverse_cost column of the SQL generated set of rows will be used for the cost of the traversal of the edge in the opposite direction.

Returns set of pgr_costResult[]:

seq:row sequence
id1:source node ID
id2:target node ID
cost:cost to traverse from id1 to id2

History

  • New in version 2.0.0

Examples

SELECT seq, id1 AS from, id2 AS to, cost
    FROM pgr_apspWarshall(
        'SELECT id, source, target, cost FROM edge_table',
        false, false
    );

 seq | from | to | cost
-----+------+----+------
   0 |    1 |  1 |    0
   1 |    1 |  2 |    1
   2 |    1 |  3 |    0
   3 |    1 |  4 |   -1
[...]

The query uses the Sample Data network.