Why do I get very inconsistent Google Geocode API results? - google-api

Question

I have a list of a few thousand locations for which I need to find the coordinates. I'm using Google Geocode API for this.
The information I have is something like "USA, California, Napa Valley"
So my Geocode call would look something like this:
https://maps.googleapis.com/maps/api/geocode/json?address=Napa+Valley,California,USA&key=<apikey>
(I put them in reverse order and replace spaces with "+" characters)
I'm of course mostly interested in the values found under ['results'][0]['geometry']['location'] key (where latitude and longitude will be found).
Now in a lot of cases I get very different results by simply waiting a few hours or 1 day and making the call again. And I make those calls using the exact same data, same parameters, same everything
Usually the coordinates are different by a fraction of a degree or at most 1.0 - 1.5 degrees. For example 39.8 latitude yesterday becomes 40.4 latitude today. And then it becomes 40.1. And then a day after it comes back to 39.8. And then it's 40.25. And so on...
However in some extreme cases the differences are massive.
Actual concrete example:
https://maps.googleapis.com/maps/api/geocode/json?address=Côtes+du+Rhône-Brézème,Northern+Rhône,Rhône,France&key=<apikey>
The result will be something like:
{
"results": [
{
.....
"formatted_address": "Rhône",
"geometry": {
.........
"location": {
"lat": 44.952398,
"lng": 6.4840823
}
},
"partial_match": true,
......
}
],
"status": "OK"
}
So it's somewhat correctly identified as the Rhone region in France.
However if I wait just a few minutes and make the call again, I get this:
{
"results" : [
{
......
"formatted_address" : "148 Chambers St A, New York, NY 10007, USA",
"geometry" : {
"location" : {
"lat" : 40.715666,
"lng" : -74.009906
},
......
},
.....
}
],
"status" : "OK"
}
Since when is Rhone/France even close to New-York ?
And this is the annoying part: I don't change anything about the URL. I simply make the EXACT same call a few minutes apart.
My thinking was that it was caused by me not properly encoding the URL.
However, while this may be true, I found it happens for queries that use NO special characters at all, for example something like Clarksburg,California,USA. In this case though I get 2 different results (coordinates), both in California, about 200 miles from each other.
Why does this happen? I need consistent results by this API. I don't need extreme precision or something like that. But at least some strong consistency.
I can't just go through a few thousand locations and put them manually in Google-Maps website to find their coordinates. It would take me 1 week of non-stop work...

Answer 1

This looks like a bug that would be best reported in the Google Maps APIs public issue tracker at https://issuetracker.google.com/code/p/gmaps-api-issues/