# pgr_bdDijkstraCost¶

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

Availability:

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

Support

• Supported versions: current(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   Inner SQL 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¶

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 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.