pgr_bridges

pgr_bridges - Return the bridges of an undirected graph.

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Boost Graph Inside

Availability

  • Version 3.0.0
    • Return columns change: seq is removed
    • Official function
  • Version 2.5.0
    • New experimental function

Support

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

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:

  • The signature is for an undirected graph.
  • 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 edge_table'
);
 edge
------
    1
    6
    7
   14
   17
   18
(6 rows)

Parameters

Parameter Type Default Description
Edges SQL TEXT   Inner query as described bellow.

Inner query

edges SQL:an SQL query of an undirected graph, which should return a set of rows with the following columns:
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 (edge)

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

See Also

Indices and tables