MongoDB vs SolR

http://stackoverflow.com/questions/3215029/nosql-mongodb-vs-lucene-or-solr-as-your-databaseThis is a great question, something I have pondered over quite a bit. I will summarize my lessons learned:

1. You can easily use Lucene/Solr in lieu of MongoDB for pretty much all situations, but not vice versa. Grant Ingersoll’s post sums it up here.
2. MongoDB etc. seem to serve a purpose where there is no requirement of searching and/or faceting. It appears to be a simpler and arguably easier transition for programmers detoxing from the RDBMS world. Unless one’s used to it Lucene & Solr have a steeper learning curve.
3. There aren’t many examples of using Lucene/Solr as a datastore, but Guardian has made some headway and summarize this in an excellent slide-deck, but they too are non-committal on totally jumping on Solr bandwagon and “investigating” combining Solr with CouchDB.
4. Finally, I will offer our experience, unfortunately cannot reveal much about the business-case. We work on the scale of several TB of data, a near real-time application. After investigating various combinations, decided to stick with Solr. No regrets thus far (6-months & counting) and see no reason to switch to some other.

Summary: if you do not have a search requirement, Mongo offers a simple & powerful approach. However if search is key to your offering, you are likely better off sticking to one tech (Solr/Lucene) and optimizing the heck out of it – fewer moving parts.