pgr_biconnectedComponents¶
pgr_biconnectedComponents
— Return the biconnected components of an undirected graph.
In particular, the algorithm implemented by Boost.Graph.
Availability
Version 3.0.0
Return columns change:
n_seq
is removedseq
changed type toBIGINT
Official function
Version 2.5.0
New experimental function
Support
Description¶
The biconnected components of an undirected graph are the maximal subsets of vertices such that the removal of a vertex from particular component will not disconnect the component. Unlike connected components, vertices may belong to multiple biconnected components. Vertices can be present in multiple biconnected components, but each edge can only be contained in a single biconnected component.
The main characteristics are:
The signature is for an undirected graph.
Components are described by edges.
The returned values are ordered:
component ascending.
edge ascending.
Running time: \(O(V + E)\)
Signatures¶
pgr_biconnectedComponents(Edges SQL)
RETURNS SET OF (seq, component, edge)
OR EMPTY SET
 Example
The biconnected components of the graph
SELECT * FROM pgr_biconnectedComponents(
'SELECT id, source, target, cost, reverse_cost FROM edge_table'
);
seq  component  edge
++
1  1  1
2  2  2
3  2  3
4  2  4
5  2  5
6  2  8
7  2  9
8  2  10
9  2  11
10  2  12
11  2  13
12  2  15
13  2  16
14  6  6
15  7  7
16  14  14
17  17  17
18  18  18
(18 rows)
Parameters¶
Parameter 
Type 
Default 
Description 

Edges SQL 

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 

Identifier of the edge. 

source 

Identifier of the first end point vertex of the edge. 

target 

Identifier of the second end point vertex of the edge. 

cost 

Weight of the edge (source, target)


reverse_cost 

1 
Weight of the edge (target, source),

Where:
 ANYINTEGER
SMALLINT, INTEGER, BIGINT
 ANYNUMERICAL
SMALLINT, INTEGER, BIGINT, REAL, FLOAT
Result Columns¶
Returns set of (seq, component, edge)
Column 
Type 
Description 

seq 

Sequential value starting from 1. 
component 

Component identifier. It is equal to the minimum edge identifier in the component. 
edge 

Identifier of the edge. 
See Also¶
The queries use the Sample Data network.
Boost: Biconnected components
wikipedia: Biconnected component
Indices and tables