One thing that bothers me is people who talk about "SQL databases vs. NoSQL databases." That's like framing a debate on transportation as "Cars vs. Not Cars," where "Not Cars" includes bicycles, planes, buses, subways, boats, zeppelins, etc. etc.
If you take CouchDB, Redis, MongoDB, and all the other "NoSQL" databases and compare them, the only thing they share in common is that they do not use a relational data model or SQL. The way the word "NoSQL" is used, however, implies that they are some kind of united front against SQL databases, which is not the case at all. (It's why I am not a big fan of the term.)
Just like you would not use bicycles, planes, subways, and boats for the same things, you would not use CouchDB, Redis, MongoDB, and Cassandra for the same things. If you're choosing a database just because it's "NoSQL," then you are completely missing the point.
I think the problem is the term NoSQL itself, originally was penned as Not Only SQL. But everyone now looks at the term with No being the actual word No in relation to SQL, as if there is some war between SQL and not...SQL. I think that alone is causing more heartburn than needed between the two camps.
If you take CouchDB, Redis, MongoDB, and all the other "NoSQL" databases and compare them, the only thing they share in common is that they do not use a relational data model or SQL. The way the word "NoSQL" is used, however, implies that they are some kind of united front against SQL databases, which is not the case at all. (It's why I am not a big fan of the term.)
Just like you would not use bicycles, planes, subways, and boats for the same things, you would not use CouchDB, Redis, MongoDB, and Cassandra for the same things. If you're choosing a database just because it's "NoSQL," then you are completely missing the point.