pgrouting: Geospatial Routing - Supabase

pgRouting is Postgres and PostGIS extension adding geospatial routing functionality.

The core functionality of pgRouting is a set of path finding algorithms including:

All Pairs Shortest Path, Johnson’s Algorithm
All Pairs Shortest Path, Floyd-Warshall Algorithm
Shortest Path A*
Bi-directional Dijkstra Shortest Path
Bi-directional A* Shortest Path
Shortest Path Dijkstra
Driving Distance
K-Shortest Path, Multiple Alternative Paths
K-Dijkstra, One to Many Shortest Path
Traveling Sales Person
Turn Restriction Shortest Path (TRSP)

Enable the extension

<Tabs scrollable size="small" type="underlined" defaultActiveId="dashboard" queryGroup="database-method"

Go to the Database page in the Dashboard.
Click on Extensions in the sidebar.
Search for pgrouting and enable the extension.

</TabPanel> <TabPanel id="sql" label="SQL"> ```sql -- Enable the "pgRouting" extension create extension pgrouting cascade;

-- Disable the "pgRouting" extension drop extension if exists pgRouting;


Even though the SQL code is `create extension`, this is the equivalent of enabling the extension.
To disable an extension you can call `drop extension`.

</TabPanel>
</Tabs>

## Example

As an example, we'll solve the [traveling salesperson problem](https://en.wikipedia.org/wiki/Travelling_salesman_problem) using the `pgRouting`'s `pgr_TSPeuclidean` function from some PostGIS coordinates.

A summary of the traveling salesperson problem is, given a set of city coordinates, solve for a path that goes through each city and minimizes the total distance traveled.

First we populate a table with some X, Y coordinates
```sql
create table wi29 (
  id bigint,
  x float,
  y float,
  geom gis.geometry
);

insert into wi29 (id, x, y)
values
  (1,20833.3333,17100.0000),
  (2,20900.0000,17066.6667),
  (3,21300.0000,13016.6667),
  (4,21600.0000,14150.0000),
  (5,21600.0000,14966.6667),
  (6,21600.0000,16500.0000),
  (7,22183.3333,13133.3333),
  (8,22583.3333,14300.0000),
  (9,22683.3333,12716.6667),
  (10,23616.6667,15866.6667),
  (11,23700.0000,15933.3333),
  (12,23883.3333,14533.3333),
  (13,24166.6667,13250.0000),
  (14,25149.1667,12365.8333),
  (15,26133.3333,14500.0000),
  (16,26150.0000,10550.0000),
  (17,26283.3333,12766.6667),
  (18,26433.3333,13433.3333),
  (19,26550.0000,13850.0000),
  (20,26733.3333,11683.3333),
  (21,27026.1111,13051.9444),
  (22,27096.1111,13415.8333),
  (23,27153.6111,13203.3333),
  (24,27166.6667,9833.3333),
  (25,27233.3333,10450.0000),
  (26,27233.3333,11783.3333),
  (27,27266.6667,10383.3333),
  (28,27433.3333,12400.0000),
  (29,27462.5000,12992.2222);

Next we use the pgr_TSPeuclidean function to find the best path.

sql

select
    *
from
     pgr_TSPeuclidean($$select * from wi29$$)

sql

 seq | node |       cost       |     agg_cost     
-----+------+------------------+------------------
   1 |    1 |                0 |                0
   2 |    2 |  74.535614157127 |  74.535614157127
   3 |    6 | 900.617093380362 | 975.152707537489
   4 |   10 | 2113.77757765045 | 3088.93028518793
   5 |   11 | 106.718669615254 | 3195.64895480319
   6 |   12 | 1411.95293791574 | 4607.60189271893
   7 |   13 | 1314.23824873744 | 5921.84014145637
   8 |   14 | 1321.76283931305 | 7243.60298076942
   9 |   17 | 1202.91366735569 |  8446.5166481251
  10 |   18 | 683.333268292684 | 9129.84991641779
  11 |   15 | 1108.05137466134 | 10237.9012910791
  12 |   19 | 772.082339448903 |  11009.983630528
  13 |   22 | 697.666150054665 | 11707.6497805827
  14 |   23 | 220.141999627513 | 11927.7917802102
  15 |   21 | 197.926372783442 | 12125.7181529937
  16 |   29 | 440.456596290771 | 12566.1747492844
  17 |   28 | 592.939989005405 | 13159.1147382898
  18 |   26 | 648.288376333318 | 13807.4031146231
  19 |   20 | 509.901951359278 | 14317.3050659824
  20 |   25 | 1330.83095428717 | 15648.1360202696
  21 |   27 |  74.535658878487 | 15722.6716791481
  22 |   24 | 559.016994374947 |  16281.688673523
  23 |   16 | 1243.87392358622 | 17525.5625971092
  24 |    9 |  4088.0585364911 | 21613.6211336004
  25 |    7 |  650.85409697993 | 22264.4752305803
  26 |    3 | 891.004385199336 | 23155.4796157796
  27 |    4 | 1172.36699411442 |  24327.846609894
  28 |    8 | 994.708187806297 | 25322.5547977003
  29 |    5 | 1188.01888359478 | 26510.5736812951
  30 |    1 | 2266.91173136004 | 28777.4854126552

Resources

Official pgRouting documentation