pgr_biconnectedComponents
— Return the biconnected components of an undirected graph.
In particular, the algorithm implemented by Boost.Graph.
Availability
n_seq
is removedseq
changed type to BIGINT
Support
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:
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)
Parameter | Type | Default | Description |
---|---|---|---|
Edges SQL | TEXT |
Inner query as described below. |
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)
|
|
reverse_cost | ANY-NUMERICAL |
-1 | Weight of the edge (target, source),
|
Where:
ANY-INTEGER: | SMALLINT, INTEGER, BIGINT |
---|---|
ANY-NUMERICAL: | SMALLINT, INTEGER, BIGINT, REAL, FLOAT |
Returns set of (seq, component, edge)
Column | Type | Description |
---|---|---|
seq | BIGINT |
Sequential value starting from 1. |
component | BIGINT |
Component identifier. It is equal to the minimum edge identifier in the component. |
edge | BIGINT |
Identifier of the edge. |
Indices and tables