dijkstra (#16) - Difference between dijkstra_sp and dijkstra_sp_delta (#303) - Message List

Wrapper functions were made to reduce response time of pgRouting. The response time consist of 2 main parts - loading data and calculating result. The first part very much depends on a size of data. To reduce this size we take only a bounding box around start and end points, but for the safety we need it to be a little bit bigger. Delta functions accept one more parameter which tells how much bigger a bounding box should be. The value is the distance between source/target point and the border of the bounding box (in your projection units). We call this parameter delta.

If you make the value of delta is not big enough, some important roads might be outside selected area and that's why your results are different.

Hope it helps.

Anton.