What drove the change from MySQL to PostgreSQL as the OSM db system?

Unlike Postgresql, MySQL 5.1 seems to have all the GIS column types inbuilt (though I’ve not used them, so there might be less there than meets the eye). As far as I’m aware, MySQL is also the more strongly supported of the two.

I could understand if the switch had gone the other way, or from MySQL to MariaDB if the issue is keeping it non-commercial, but going from MySQL to Postgresql is a puzzle to me. If it’s already been explained somewhere, could someone give me a pointer?

(I suppose I should declare my interest: I understand MySQL pretty well already, but Postgresql not at all yet, so it would have been more convenient for me if MySQL were still the system of choice. I know: selfish selfish

Thanks!

I had wondered about that one also, and this post explains it: http://blog.cleverelephant.ca/2009/04/openstreetmap-moves-to-postgresql.html

Whether the db supported GIS extensions or not was no issue at all, since the OSM db doesn’t use them.

Thanks, both. I expect I’m too new to OSM to really understand the issues, because I couldn’t connect Paul Ramsey’s explanation with anything I think I understand about storing and retrieving maps. Ignorance is a terrible thing!