pgr_bridges

pgr_bridges - Return the bridges of an undirected graph.

_images/boost-inside.jpeg

Boost Graph Inside

Availability

Description

A bridge is an edge of an undirected graph whose deletion increases its number of connected components. This implementation can only be used with an undirected graph.

The main characteristics are:

  • Works for undirected graphs.
  • The returned values are ordered:
    • edge ascending
  • Running time: \(O(E * (V + E))\)

Signatures

pgr_bridges(Edges SQL)
RETURNS SET OF (edge)
OR EMPTY SET
Example:The bridges of the graph 
SELECT * FROM pgr_bridges(
  'SELECT id, source, target, cost, reverse_cost FROM edges'
);
 edge
------
    1
    6
    7
   14
   17
   18
(6 rows)
_images/bridge_sampledata.png

Parameters

Parameter Type Description
Edges SQL TEXT Edges SQL as described below.

Inner Queries

Edges SQL

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)
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 (edge)

Column Type Description
edge BIGINT Identifier of the edge that is a bridge.

See Also

Indices and tables