pgr_articulationPoints  pgRouting Manual (3.3)
pgr_articulationPoints
pgr_articulationPoints
 Return the articulation points of an undirected graph.
Availability

Version 3.0.0

Return columns change:
seq
is removed 
Official function


Version 2.5.0

New experimental function

Description
Those vertices that belong to more than one biconnected component are called articulation points or, equivalently, cut vertices. Articulation points are vertices whose removal would increase the number of connected components in the graph. 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:

node ascending


Running time: \(O(V + E)\)
Signatures
pgr_articulationPoints(Edges SQL)
RETURNS SET OF (node)
OR EMPTY SET
 Example :

The articulation points of the graph
SELECT * FROM pgr_articulationPoints(
'SELECT id, source, target, cost, reverse_cost FROM edge_table'
);
node

2
5
8
10
(4 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
(node)
Column 
Type 
Description 

node 

Identifier of the vertex. 
See Also

The queries use the Sample Data network.

wikipedia: Biconnected component
Indices and tables