I completely agree with the parents about Map Reduce. However I would justify using MongoDB for totally different reasons, not scalability. It is easy to setup,

I completely agree with the parents about Map Reduce. However I would justify using MongoDB for totally different reasons, not scalability. It is easy to setup, easy to manage and above all easy to use, which are all important factors if you are developing something new. However it does have a few "less than perfect" solutions to some problems (removing data does not always free disk space, no support for big decimals,...) and it definitely takes some getting used to. But it is a quite acceptable solution for "small data" too. Edit: ...and I wouldn't dream of using MongoDB's implementation of MapReduce.