Reverse Geocoding of Milestones (marker posts in Km)
I would like to know you opinion about what could be the best approach to implement a Reverse Geocoding Service, if possible in ArcGIS Online, where you send X,Y coordinates and receives back the nearest milestone to it. Eg.: x,y -> "Milestone" 404,2 Km
My idea was to create a feature service in ArcGIS Online with the "milestones" for Spain, 100K points aprox. I'm also considering to create a 1M points feature service, to incorporate the hectometer, so that I can get back the Km and the hectometer. Does it make sense?
I'm aware of possible performance problems, 
and I've already figured out workarounds such as various services per road, province, etc... It's is not my intention to render these points in a Map, I only want to search for features and I wonder if 100K or 1M points FS would be fast enough in ArcGIS Online
Thank you very much and kind regards,
