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(3.1) 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 below.

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