pgr_bdDijkstra

pgr_bdDijkstra - Returns the shortest path(s) using Bidirectional Dijkstra algorithm.

images/boost-inside.jpeg

Boost Graph Inside

Availability:

  • Version 3.2.0

    • New proposed function:

      • pgr_bdDijkstra(Combinations)

  • Version 3.0.0

    • Official function

  • Version 2.5.0

    • New Proposed functions:

      • pgr_bdDijkstra(One to Many)

      • pgr_bdDijkstra(Many to One)

      • pgr_bdDijkstra(Many to Many)

  • Version 2.4.0

    • Signature change on pgr_bdDijsktra(One to One)

      • Old signature no longer supported

  • Version 2.0.0

    • Official pgr_bdDijkstra(One to One)

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_bdDijkstra(Edges SQL, start_vid,  end_vid  [, directed])
pgr_bdDijkstra(Edges SQL, start_vid,  end_vids [, directed])
pgr_bdDijkstra(Edges SQL, start_vids, end_vid  [, directed])
pgr_bdDijkstra(Edges SQL, start_vids, end_vids [, directed])
pgr_bdDijkstra(Edges SQL, Combinations SQL [, directed]) -- Proposed on v3.2

RETURNS SET OF (seq, path_seq [, start_vid] [, end_vid], node, edge, cost, agg_cost)
OR EMPTY SET

Using defaults

pgr_bdDijkstra(Edges SQL, start_vid, end_vid)
RETURNS SET OF (seq, path_seq, node, edge, cost, agg_cost)
OR EMPTY SET
Example :

From vertex \(2\) to vertex \(3\)

SELECT * FROM pgr_bdDijkstra(
    'SELECT id, source, target, cost, reverse_cost FROM edge_table',
    2, 3
);
 seq  path_seq  node  edge  cost  agg_cost
-----+----------+------+------+------+----------
   1         1     2     4     1         0
   2         2     5     8     1         1
   3         3     6     9     1         2
   4         4     9    16     1         3
   5         5     4     3     1         4
   6         6     3    -1     0         5
(6 rows)

One to One

pgr_bdDijkstra(Edges SQL, start_vid, end_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_bdDijkstra(
    'SELECT id, source, target, cost, reverse_cost FROM edge_table',
    2, 3,
    false
);
 seq  path_seq  node  edge  cost  agg_cost
-----+----------+------+------+------+----------
   1         1     2     2     1         0
   2         2     3    -1     0         1
(2 rows)

One to many

pgr_bdDijkstra(Edges SQL, start_vid, end_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_bdDijkstra(
    'SELECT id, source, target, cost, reverse_cost FROM edge_table',
    2, ARRAY[3, 11]);
 seq  path_seq  end_vid  node  edge  cost  agg_cost
-----+----------+---------+------+------+------+----------
   1         1        3     2     4     1         0
   2         2        3     5     8     1         1
   3         3        3     6     9     1         2
   4         4        3     9    16     1         3
   5         5        3     4     3     1         4
   6         6        3     3    -1     0         5
   7         1       11     2     4     1         0
   8         2       11     5     8     1         1
   9         3       11     6    11     1         2
  10         4       11    11    -1     0         3
(10 rows)

Many to One

pgr_bdDijkstra(Edges SQL, start_vids, end_vid [, 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_bdDijkstra(
    'SELECT id, source, target, cost, reverse_cost FROM edge_table',
    ARRAY[2, 7], 3);
 seq  path_seq  start_vid  node  edge  cost  agg_cost
-----+----------+-----------+------+------+------+----------
   1         1          2     2     4     1         0
   2         2          2     5     8     1         1
   3         3          2     6     9     1         2
   4         4          2     9    16     1         3
   5         5          2     4     3     1         4
   6         6          2     3    -1     0         5
   7         1          7     7     6     1         0
   8         2          7     8     7     1         1
   9         3          7     5     8     1         2
  10         4          7     6     9     1         3
  11         5          7     9    16     1         4
  12         6          7     4     3     1         5
  13         7          7     3    -1     0         6
(13 rows)

Many to Many

pgr_bdDijkstra(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_bdDijkstra(
    'SELECT id, source, target, cost, reverse_cost FROM edge_table',
    ARRAY[2, 7], ARRAY[3, 11]);
 seq  path_seq  start_vid  end_vid  node  edge  cost  agg_cost
-----+----------+-----------+---------+------+------+------+----------
   1         1          2        3     2     4     1         0
   2         2          2        3     5     8     1         1
   3         3          2        3     6     9     1         2
   4         4          2        3     9    16     1         3
   5         5          2        3     4     3     1         4
   6         6          2        3     3    -1     0         5
   7         1          2       11     2     4     1         0
   8         2          2       11     5     8     1         1
   9         3          2       11     6    11     1         2
  10         4          2       11    11    -1     0         3
  11         1          7        3     7     6     1         0
  12         2          7        3     8     7     1         1
  13         3          7        3     5     8     1         2
  14         4          7        3     6     9     1         3
  15         5          7        3     9    16     1         4
  16         6          7        3     4     3     1         5
  17         7          7        3     3    -1     0         6
  18         1          7       11     7     6     1         0
  19         2          7       11     8     7     1         1
  20         3          7       11     5    10     1         2
  21         4          7       11    10    12     1         3
  22         5          7       11    11    -1     0         4
(22 rows)

Combinations

pgr_bdDijkstra(Edges SQL, Combinations SQL [, directed])
RETURNS SET OF (seq, path_seq, start_vid, end_vid, node, edge, cost, agg_cost)
OR EMPTY SET
Example :

Using a combinations table on a directed graph.

SELECT * FROM pgr_bdDijkstra(
    'SELECT id, source, target, cost, reverse_cost FROM edge_table',
    'SELECT * FROM ( VALUES (2, 3), (7, 11) ) AS t(source, target)');
 seq  path_seq  start_vid  end_vid  node  edge  cost  agg_cost
-----+----------+-----------+---------+------+------+------+----------
   1         1          2        3     2     4     1         0
   2         2          2        3     5     8     1         1
   3         3          2        3     6     9     1         2
   4         4          2        3     9    16     1         3
   5         5          2        3     4     3     1         4
   6         6          2        3     3    -1     0         5
   7         1          7       11     7     6     1         0
   8         2          7       11     8     7     1         1
   9         3          7       11     5    10     1         2
  10         4          7       11    10    12     1         3
  11         5          7       11    11    -1     0         4
(11 rows)

Parameters

Parameter

Type

Default

Description

Edges SQL

TEXT

Edges query as described below

Combinations SQL

TEXT

Combinations 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 queries

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

Combinations query

Column

Type

Default

Description

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.

Where:

ANY-INTEGER :

SMALLINT, INTEGER, BIGINT

Result Columns

Returns set of (seq, path_id, path_seq [, start_vid] [, end_vid], node, edge, cost, agg_cost)

Column

Type

Description

seq

INT

Sequential value starting from 1 .

path_id

INT

Path identifier. Has value 1 for the first of a path. Used when there are multiple paths for the same start_vid to end_vid combination.

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 .

See Also

Indices and tables