Thank you for responding. Since my line_string is written a geojson, I would have to sort that part out. So for now manual calculation is easier.
If I understand correctly the linestring_column would have to be a geometry.
My geojson looks like this: {"type":"LineString","coordinates":[[-118.25573325622828,34.045980983930036],[-118.2428586529568,34.03517030952861],[-118.20938468445094,34.049394594819795],[-118.21710944641383,34.03517030952861]]} so something thinks it’s a line_string, but not SQL.