When should I use a NoSQL database instead of a relational database? Is it okay to use both on the same site?

Question

What are the advantages of using NoSQL databases? I\'ve read a lot about them lately, but I\'m still unsure why I would want to implement one, and under what circumstances I

Answer 1

Martin Fowler has an excellent video which gives a good explanation of NoSQL databases. The link goes straight to his reasons to use them, but the whole video contains good information.

1. You have large amounts of data - especially if you cannot fit it all on one physical server as NoSQL was designed to scale well.

2. Object-relational impedance mismatch - Your domain objects do not fit well in a relaitional database schema. NoSQL allows you to persist your data as documents (or graphs) which may map much more closely to your data model.