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Database

pgrouting: Geospatial Routing

pgRouting is PostgreSQL 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

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

Example

As an example, we'll solve the traveling salesman problem using the pgRouting's pgr_TSPeuclidean function from some PostGIS coordinates.

A summary of the traveling salesman 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


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

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


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


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

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