When would someone use MongoDB (or similar) over traditional RDMS?
How well the SQL and NoSQL go head-to-head. I read somewhere that SQL databases are not well for data that is well structured or has some graph-iness associated with it. Is it really the case?
Apart form Facebook, Google, and some other big players on the web, I don't know how well small-players and start-ups have used these tools. I found another similar question about the same here. But I couldn't gather much stats from here. These are certain specific cases, and is there a general pattern (like the one mentioned above) for which these NoSQL databases can be used?
How wise will it be for a start-up to go for a NoSQL database if the developers know that the amount of data involved will be a little large and is well structured, but requires frequent CRUD operations?
Here on stackoverflow, one can find questions about when not to use SQL, but are there any scenarios when one should avoid using NoSQL databases? Also, how effective will it be to use both in parallel so that we get the best of them both?
One last question, do these distributed NoSQL databases perform equally well when they are used in a single-node setup?