Is MongoDB a valid alternative to relational db + lucene? [closed]

Question

On a new project I need a hard use of lucene for a searcher implementation. This searcher will be a very important (and big) piece of the project. Is valid or convenient replacing Relational Database + Lucene with MongoDb?

edit: Ok, I will clarify: I'm not asking about risk, I can pay that price in this project. My point is: Is MongoDB oriented to this kind of thing? Can I make a full search engine with the same perfomance as I can get on Lucene?. A friend point me out MongoDB as alternative, but I don't see if the Lucene performance comes with the document alternative (and then, I will see it in MongoDB too), or, in other hand, the inverted index and optimitizations are complety independant of document orientation.

Answer 1

Technically you can do full text search with MongoDB, but you're missing out on a lot that a full text search provider has to offer. I love MongoDB, but I'd couple it with a full text search provider (such as Lucene or Sphinx) if time to implementation is at all a concern. I think MongoDB's convenient ability to index word arrays is better left to tagging and searching based on tagging than full text search.

Search (Information Retrieval) isn't just about grabbing any documents that match, if you want your search results to have any relevance at all you're going to need something along the lines of TF-IDF, phrase matching (words in a sequence score higher) or any number of other IR techniques to improve search precision. If you use MongoDB you'll need to implement it all from scratch.

If you really want to implement it all from scratch but not bother with the raw storage side of things, MongoDB is pretty close to the best DB store that you could implement it on top of (can't think of many others), but that still doesn't make it a great option.