pgDijkstra-go

pgDijkstra-go is a native Shortest Path Search function for PostgreSQL databases. This is written using the Go Language and uses a very Fast GoLang Dijkstra engine which enables pgDijkstra-go to perform long distance searches even in very dense networks.

Build and Install

To build and install the function the following has to be done:

• edit install.sh and change the GO_DB parameter to point to the correct PostgreSQL database that will be used to install the function.

• run the compile.sh script to create libPgDijkstra-go.so library file.

./compile.sh

• run the install.sh to create a SQL function in the PostgreSQL database that will call the native function in the created library file.

./install.sh
CREATE FUNCTION

Usage

By this point, the sample function pg_dijkstra_go already has been installed and can now be run.

go=# \df pg_dijkstra_go
                             List of functions
 Schema |      Name      | Result data type |  Argument data types   | Type 
--------+----------------+------------------+------------------------+------
 public | pg_dijkstra_go | text             | text, integer, integer | func
(1 row)

The pg_dijkstra_go function takes 3 parameters:

1. A JSON Formatted Text that contains the Graph Data.
2. The Source Node ID of the requested Shortest Path.
3. The Target Node ID of the requested Shortetest Path

And the Graph Data in JSON Text format should contain the following data:

• ID of the Edge
• Source Node ID
• Target Node ID
• Cost of the Edge

Examples

• Getting a Shortest Path that will return a Text containg the edge ids in JSON format:

select pg_dijkstra_go((select json_agg(graph)::text as graph from (select id,source,target,cost from pgrserver) graph),1209274,1844841);

• Transforming the returned JSON Text into a set of records

select * from json_to_recordset( (select pg_dijkstra_go((select json_agg(graph)::text from (select id,source,target,cost from pgrserver) graph),1209274,749290)::json) ) as x (edge_id int) ;

• Inserting the results of the Shortest Path Search into a Table:

insert into dijkstra_result  select id,geom from pgrserver where id in (select edge_id from json_to_recordset( (select pg_dijkstra_go((select json_agg(graph)::text from (select id,source,target,cost from pgrserver) graph),1209274,749290)::json) ) as x (edge_id int));