pgr_bdDijkstraCost

pgr_bdDijkstraCost — Returns the shortest path(s)’s cost using Bidirectional Dijkstra algorithm.

_images/boost-inside.jpeg

Boost Graph Inside

Availability:

  • Version 3.0.0
    • Official function
  • Version 2.5.0
    • New proposed function

Support

  • Supported versions: current(3.1) 3.0 2.6
  • Unsupported versions: 2.5

Description

The main characteristics are:

  • Process is done only on edges with positive costs.
  • Values are returned when there is a path.
  • When the starting vertex and ending vertex are the same, there is no path.
    • The agg_cost the non included values (v, v) is 0
  • When the starting vertex and ending vertex are the different and there is no path:
    • The agg_cost the non included values (u, v) is \(\infty\)
  • Running time (worse case scenario): \(O((V \log V + E))\)
  • For large graphs where there is a path bewtween the starting vertex and ending vertex:
    • It is expected to terminate faster than pgr_dijkstra

Signatures

Summary

pgr_bdDijkstraCost(edges_sql, from_vid,  to_vid  [, directed])
pgr_bdDijkstraCost(edges_sql, from_vid,  to_vids [, directed])
pgr_bdDijkstraCost(edges_sql, from_vids, to_vid  [, directed])
pgr_bdDijkstraCost(edges_sql, from_vids, to_vids [, directed])

RETURNS SET OF (start_vid, end_vid, agg_cost)
OR EMPTY SET

Using default

pgr_bdDijkstraCost(edges_sql, from_vid,  to_vid)
RETURNS SET OF (seq, path_seq, node, edge, cost, agg_cost)
OR EMPTY SET
Example:From vertex \(2\) to vertex \(3\) on a directed graph
SELECT * FROM pgr_bdDijkstraCost(
    'SELECT id, source, target, cost, reverse_cost FROM edge_table',
    2, 3
);
 start_vid | end_vid | agg_cost
-----------+---------+----------
         2 |       3 |        5
(1 row)

One to One

pgr_bdDijkstraCost(edges_sql, from_vid,  to_vid  [, directed])
RETURNS SET OF (seq, path_seq, node, edge, cost, agg_cost)
OR EMPTY SET
Example:From vertex \(2\) to vertex \(3\) on an undirected graph
SELECT * FROM pgr_bdDijkstraCost(
    'SELECT id, source, target, cost, reverse_cost FROM edge_table',
    2, 3,
    false
);
 start_vid | end_vid | agg_cost
-----------+---------+----------
         2 |       3 |        1
(1 row)

One to Many

pgr_bdDijkstraCost(edges_sql, from_vid,  to_vids [, directed])
RETURNS SET OF (seq, path_seq, end_vid, node, edge, cost, agg_cost)
OR EMPTY SET
Example:From vertex \(2\) to vertices \(\{3, 11\}\) on a directed graph
SELECT * FROM pgr_bdDijkstraCost(
    'SELECT id, source, target, cost, reverse_cost FROM edge_table',
    2, ARRAY[3, 11]);
 start_vid | end_vid | agg_cost
-----------+---------+----------
         2 |       3 |        5
         2 |      11 |        3
(2 rows)

Many to One

pgr_bdDijkstraCost(edges_sql, from_vids, to_vids [, directed])
RETURNS SET OF (seq, path_seq, start_vid, node, edge, cost, agg_cost)
OR EMPTY SET
Example:From vertices \(\{2, 7\}\) to vertex \(3\) on a directed graph
SELECT * FROM pgr_bdDijkstraCost(
    'SELECT id, source, target, cost, reverse_cost FROM edge_table',
    ARRAY[2, 7], 3);
 start_vid | end_vid | agg_cost
-----------+---------+----------
         2 |       3 |        5
         7 |       3 |        6
(2 rows)

Many to Many

pgr_bdDijkstraCost(edges_sql, start_vids, end_vids [, directed])
RETURNS SET OF (seq, path_seq, start_vid, end_vid, node, edge, cost, agg_cost)
OR EMPTY SET
Example:From vertices \(\{2, 7\}\) to vertices \(\{3, 11\}\) on a directed graph
SELECT * FROM pgr_bdDijkstraCost(
    'SELECT id, source, target, cost, reverse_cost FROM edge_table',
    ARRAY[2, 7], ARRAY[3, 11]);
 start_vid | end_vid | agg_cost
-----------+---------+----------
         2 |       3 |        5
         2 |      11 |        3
         7 |       3 |        6
         7 |      11 |        4
(4 rows)

Parameters

Parameter Type Default Description
Edges SQL TEXT   Edges query as described below
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.
directed BOOLEAN true
  • When true Graph is considered Directed
  • When false the graph is considered as Undirected.

Inner query

Edges query

Column Type Default Description
id ANY-INTEGER   Identifier of the edge.
source ANY-INTEGER   Identifier of the first end point vertex of the edge.
target ANY-INTEGER   Identifier of the second end point vertex of the edge.
cost ANY-NUMERICAL  

Weight of the edge (source, target)

  • When negative: edge (source, target) does not exist, therefore it’s not part of the graph.
reverse_cost ANY-NUMERICAL -1

Weight of the edge (target, source),

  • When negative: edge (target, source) does not exist, therefore it’s not part of the graph.

Where:

ANY-INTEGER:SMALLINT, INTEGER, BIGINT
ANY-NUMERICAL:SMALLINT, INTEGER, BIGINT, REAL, FLOAT

Result Columns

Returns SET OF (start_vid, end_vid, agg_cost)

Column Type Description
start_vid BIGINT Identifier of the starting vertex. Used when multiple starting vetrices are in the query.
end_vid BIGINT Identifier of the ending vertex. Used when multiple ending vertices are in the query.
agg_cost FLOAT Aggregate cost from start_vid to end_vid.