PostGIS Spiders

I had a request for some “spider diagrams” showing the connections between service centres and their customers and was given some sample data of about 140000 records.

QGIS spider/hub diagram

The data contained a customer ID and customer coordinates and a service centre ID.  Using another table of service centres I was able to add and update for each record the service centre coordinates (eastings and northings on the British National Grid EPSG:27700). Continue reading PostGIS Spiders