pgr_kruskal
— Returns the minimum spanning tree of graph using Kruskal algorithm.
Availability
This algorithm finds the minimum spanning forest in a possibly disconnected graph using Kruskal’s algorithm.
The main Characteristics are:
Summary
pgr_kruskal(edges_sql)
RETURNS SET OF (seq, edge, cost)
OR EMPTY SET
Example:  Minimum Spanning Forest 

SELECT * FROM pgr_kruskal(
'SELECT id, source, target, cost, reverse_cost
FROM edge_table'
) ORDER BY edge;
edge  cost
+
1  1
2  1
3  1
6  1
7  1
10  1
11  1
12  1
13  1
14  1
15  1
16  1
17  1
18  1
(14 rows)
Parameter  Type  Description 

Edges SQL  TEXT 
SQL query described in Inner query. 
Column  Type  Default  Description 

id  ANYINTEGER 
Identifier of the edge.  
source  ANYINTEGER 
Identifier of the first end point vertex of the edge.  
target  ANYINTEGER 
Identifier of the second end point vertex of the edge.  
cost  ANYNUMERICAL 
Weight of the edge (source, target)


reverse_cost  ANYNUMERICAL 
1  Weight of the edge (target, source),

Where:
ANYINTEGER:  SMALLINT, INTEGER, BIGINT 

ANYNUMERICAL:  SMALLINT, INTEGER, BIGINT, REAL, FLOAT 
Returns SET OF (edge, cost)
Column  Type  Description 

edge  BIGINT 
Identifier of the edge. 
cost  FLOAT 
Cost to traverse the edge. 
Indices and tables