[specialp]

I have been using MongoDB since the beta days but after many replica set/sharding bugs springing up, I am less inclined to use it. That was the major feature we used if for. Addressing this article:

-Yes you can make aggregate results using map reduce (In javascript with a single core, idempotent) and you can store the aggregates as separate documents. I do not see what is so magical about this.

-It is true that you do not have a set schema thus no migrations, but you do have to have a schema in mind for nearly everything as something has to make sense of that field.

If you add fields to a document and you already have documents in there, you are going to have to add that data to them unless you want them to be nil. If you rename a field you have to iterate all documents and add rename it. If you remove a field you have to remove it from all existing documents if you do not want to have that data around anymore. Certainly you do not HAVE to do any of this but if you are fetching meaningful data from a field you need to.

And you need to index on whatever you want to search on or the performance is terrible as Mongo is not very good on the disk so you have to keep that in mind too. I think most people were attracted to Mongo due to "no migrations" and schema but when you work with it almost any use case you find yourself using an unenforced schema and doing script based "migrations" The recent Mongo criticism is that it markets itself as a all purpose DB but in reality document stores are not that.