One of the things that we are putting into the new version of the RavenDB Website is some smarts about courses. We want to be able to figure out where a visitor is coming from, and show him relevant courses near him.
This is a fairly standard feature, I guess. But I think we solved this in an interesting fashion. First, we had to figure out how to know where a visitor is coming from. This is done via geo location. There are plenty of geo location API, such as:
The problem is that a service like that is limited to ~1000 queries per hour, and we didn’t want that. Other option include paid services, again, with either hard limits on the number of queries per hour or an open credit line. Neither option was very interesting to us.
Instead, we thought we would try something out. Max Mind is offering a database that can be used for geo location purposes. They have two options, a free database and a paid option. I took the free version for a spin.
Here is the GoeLiteCity-Blocks information:
Note that we have repeated rows per location, which allows us to map multiple ranges for each location.
And finally, we have GoLiteCity-Location, which map a location id to an actual location:
Anyone who used a relational database should be familiar with the data format, right?
I found it really interesting that MaxMind state on their site:
Note that queries made against the CSV data imported into a SQL database can take up to a few seconds. If performance is an issue, the binary format is much faster, and can handle thousands of lookups per second.
They actually have a custom binary format to allow faster queries, but I think that I can do something about this. In the next post in this series, I’ll talk about how to import this data into RavenDB and the model concerns that we have with it.