47705a8968
* fix: rewrite relative URLs when syncing to GitHub discussion Relative URLs back to supabse.com won't work in GitHub discussions, so rewrite them back to absolute URLs starting with https://supabase.com * fix: replace all supabase urls with relative urls * chore: add linting for relative urls * chore: bump linter version * Prettier --------- Co-authored-by: Chris Chinchilla <chris.ward@supabase.io>
155 lines
4.7 KiB
Plaintext
155 lines
4.7 KiB
Plaintext
---
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id: 'pgrouting'
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title: 'pgrouting: Geospatial Routing'
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description: 'Extends PostGIS with Geospatial Routing'
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---
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[`pgRouting`](http://pgrouting.org) is Postgres and [PostGIS](http://postgis.net) extension adding geospatial routing functionality.
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The core functionality of `pgRouting` is a set of path finding algorithms including:
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- All Pairs Shortest Path, Johnson’s Algorithm
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- All Pairs Shortest Path, Floyd-Warshall Algorithm
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- Shortest Path A\*
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- Bi-directional Dijkstra Shortest Path
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- Bi-directional A\* Shortest Path
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- Shortest Path Dijkstra
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- Driving Distance
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- K-Shortest Path, Multiple Alternative Paths
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- K-Dijkstra, One to Many Shortest Path
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- Traveling Sales Person
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- Turn Restriction Shortest Path (TRSP)
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## Enable the extension
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<Tabs
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scrollable
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size="small"
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type="underlined"
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defaultActiveId="dashboard"
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queryGroup="database-method"
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>
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<TabPanel id="dashboard" label="Dashboard">
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1. Go to the [Database](/dashboard/project/_/database/tables) page in the Dashboard.
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2. Click on **Extensions** in the sidebar.
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3. Search for `pgrouting` and enable the extension.
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</TabPanel>
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<TabPanel id="sql" label="SQL">
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{/* prettier-ignore */}
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```sql
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-- Enable the "pgRouting" extension
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create extension pgrouting cascade;
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-- Disable the "pgRouting" extension
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drop extension if exists pgRouting;
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```
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Even though the SQL code is `create extension`, this is the equivalent of enabling the extension.
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To disable an extension you can call `drop extension`.
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</TabPanel>
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</Tabs>
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## Example
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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.
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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.
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First we populate a table with some X, Y coordinates
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{/* prettier-ignore */}
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```sql
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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);
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```
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Next we use the `pgr_TSPeuclidean` function to find the best path.
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{/* prettier-ignore */}
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```sql
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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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```
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{/* prettier-ignore */}
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```sql
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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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```
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## Resources
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- Official [`pgRouting` documentation](https://docs.pgrouting.org/latest/en/index.html)
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