pgr_aStar
— Returns the shortest path using A* algorithm.
Availability:
The main Characteristics are:
pgr_aStar(edges_sql, start_vid, end_vid)
pgr_aStar(edges_sql, start_vid, end_vid, directed, heuristic, factor, epsilon)
Warning
Proposed functions for next mayor release.
pgr_aStar(edges_sql, start_vid, end_vids, directed, heuristic, factor, epsilon)  proposed
pgr_aStar(edges_sql, starts_vid, end_vid, directed, heuristic, factor, epsilon)  proposed
pgr_aStar(edges_sql, starts_vid, end_vids, directed, heuristic, factor, epsilon)  proposed
RETURNS SET OF (seq, path_seq [, start_vid] [, end_vid], node, edge, cost, agg_cost)
OR EMPTY SET
pgr_aStar(edges_sql, start_vid, end_vid)
RETURNS SET OF (seq, path_seq, node, edge, cost, agg_cost)
Example:  Using the defaults 

SELECT * FROM pgr_astar(
'SELECT id, source, target, cost, reverse_cost, x1, y1, x2, y2 FROM edge_table',
2, 12);
seq  path_seq  node  edge  cost  agg_cost
+++++
1  1  2  4  1  0
2  2  5  10  1  1
3  3  10  12  1  2
4  4  11  13  1  3
5  5  12  1  0  4
(5 rows)
pgr_aStar(edges_sql, start_vid, end_vid, directed, heuristic, factor, epsilon)
RETURNS SET OF (seq, path_seq, node, edge, cost, agg_cost)
Example:  Undirected using Heuristic 2 

SELECT * FROM pgr_astar(
'SELECT id, source, target, cost, reverse_cost, x1, y1, x2, y2 FROM edge_table',
2, 12,
directed := false, heuristic := 2);
seq  path_seq  node  edge  cost  agg_cost
+++++
1  1  2  2  1  0
2  2  3  3  1  1
3  3  4  16  1  2
4  4  9  15  1  3
5  5  12  1  0  4
(5 rows)
pgr_aStar(edges_sql, start_vid, end_vids, directed, heuristic, factor, epsilon)  Proposed
RETURNS SET OF (seq, path_seq, end_vid, node, edge, cost, agg_cost) or EMPTY SET
start_vid
to each end_vid
in end_vids
:directed
flag is missing or is set to true
.directed
flag is set to false
.Using this signature, will load once the graph and perform a one to one pgr_astar
where the starting vertex is fixed, and stop when all end_vids
are reached.
end_vid
in the result is used to distinguish to which path it belongs.Example: 

SELECT * FROM pgr_astar(
'SELECT id, source, target, cost, reverse_cost, x1, y1, x2, y2 FROM edge_table',
2, ARRAY[3, 12], heuristic := 2);
seq  path_seq  end_vid  node  edge  cost  agg_cost
++++++
1  1  3  2  4  1  0
2  2  3  5  8  1  1
3  3  3  6  9  1  2
4  4  3  9  16  1  3
5  5  3  4  3  1  4
6  6  3  3  1  0  5
7  1  12  2  4  1  0
8  2  12  5  10  1  1
9  3  12  10  12  1  2
10  4  12  11  13  1  3
11  5  12  12  1  0  4
(11 rows)
pgr_aStar(edges_sql, starts_vid, end_vid, directed, heuristic, factor, epsilon)  Proposed
RETURNS SET OF (seq, path_seq, start_vid, node, edge, cost, agg_cost) or EMPTY SET
start_vid
in start_vids
to one end_vid
:directed
flag is missing or is set to true
.directed
flag is set to false
.Using this signature, will load once the graph and perform several one to one pgr_aStar where the ending vertex is fixed.
start_vid
in the result is used to distinguish to which path it belongs.Example: 

SELECT * FROM pgr_astar(
'SELECT id, source, target, cost, reverse_cost, x1, y1, x2, y2 FROM edge_table',
ARRAY[7, 2], 12, heuristic := 0);
seq  path_seq  start_vid  node  edge  cost  agg_cost
++++++
1  1  2  2  4  1  0
2  2  2  5  10  1  1
3  3  2  10  12  1  2
4  4  2  11  13  1  3
5  5  2  12  1  0  4
6  1  7  7  6  1  0
7  2  7  8  7  1  1
8  3  7  5  10  1  2
9  4  7  10  12  1  3
10  5  7  11  13  1  4
11  6  7  12  1  0  5
(11 rows)
pgr_aStar(edges_sql, starts_vid, end_vids, directed, heuristic, factor, epsilon)  Proposed
RETURNS SET OF (seq, path_seq, start_vid, end_vid, node, edge, cost, agg_cost) or EMPTY SET
start_vid
in start_vids
to each end_vid
in end_vids
:directed
flag is missing or is set to true
.directed
flag is set to false
.Using this signature, will load once the graph and perform several one to Many pgr_dijkstra
for all start_vids
.
start_vid
in the result is used to distinguish to which path it belongs.The extra start_vid
and end_vid
in the result is used to distinguish to which path it belongs.
Example: 

SELECT * FROM pgr_astar(
'SELECT id, source, target, cost, reverse_cost, x1, y1, x2, y2 FROM edge_table',
ARRAY[7, 2], ARRAY[3, 12], heuristic := 2);
seq  path_seq  start_vid  end_vid  node  edge  cost  agg_cost
+++++++
1  1  2  3  2  4  1  0
2  2  2  3  5  8  1  1
3  3  2  3  6  9  1  2
4  4  2  3  9  16  1  3
5  5  2  3  4  3  1  4
6  6  2  3  3  1  0  5
7  1  7  3  7  6  1  0
8  2  7  3  8  7  1  1
9  3  7  3  5  8  1  2
10  4  7  3  6  9  1  3
11  5  7  3  9  16  1  4
12  6  7  3  4  3  1  5
13  7  7  3  3  1  0  6
14  1  2  12  2  4  1  0
15  2  2  12  5  10  1  1
16  3  2  12  10  12  1  2
17  4  2  12  11  13  1  3
18  5  2  12  12  1  0  4
19  1  7  12  7  6  1  0
20  2  7  12  8  7  1  1
21  3  7  12  5  10  1  2
22  4  7  12  10  12  1  3
23  5  7  12  11  13  1  4
24  6  7  12  12  1  0  5
(24 rows)
edges_sql:  an SQL query, which should return a set of rows with the following columns: 

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),

x1  ANYNUMERICAL 
X coordinate of source vertex.  
y1  ANYNUMERICAL 
Y coordinate of source vertex.  
x2  ANYNUMERICAL 
X coordinate of target vertex.  
y2  ANYNUMERICAL 
Y coordinate of target vertex. 
Where:
ANYINTEGER:  SMALLINT, INTEGER, BIGINT 

ANYNUMERICAL:  SMALLINT, INTEGER, BIGINT, REAL, FLOAT 
Parameter  Type  Description 

edges_sql  TEXT 
Edges SQL query as described above. 
start_vid  ANYINTEGER 
Starting vertex identifier. 
end_vid  ANYINTEGER 
Ending vertex identifier. 
directed  BOOLEAN 

heuristic  INTEGER 
(optional). Heuristic number. Current valid values 0~5. Default

factor  FLOAT 
(optional). For units manipulation. \(factor > 0\). Default 1 . see Factor 
epsilon  FLOAT 
(optional). For less restricted results. \(epsilon >= 1\). Default 1 . 
Returns set of (seq, path_seq [, start_vid] [, end_vid], node, edge, cost, agg_cost)
Column  Type  Description 

seq  INT 
Sequential value starting from 1. 
path_id  INT 
Path identifier. Has value 1 for the first of a path. Used when there are multiple paths for the same start_vid to end_vid combination. 
path_seq  INT 
Relative position in the path. Has value 1 for the beginning of a path. 
start_vid  BIGINT 
Identifier of the starting vertex. Used when multiple starting vetrices are in the query. 
end_vid  BIGINT 
Identifier of the ending vertex. Used when multiple ending vertices are in the query. 
node  BIGINT 
Identifier of the node in the path from start_vid to end_vid . 
edge  BIGINT 
Identifier of the edge used to go from node to the next node in the path sequence. 1 for the last node of the path. 
cost  FLOAT 
Cost to traverse from node using edge to the next node in the path sequence. 
agg_cost  FLOAT 
Aggregate cost from start_v to node . 