[goldenkey]

MySQL is an awful implementation of SQL. MongoDB is even more pitiful of an implementation of NoSQL. It's a Fischer price database that had a global write lock until version 2.2. What exactly don't you understand about the analogous nature of two crumby data stores?

[johannh]

So what exactly makes Mongo such a bad implementation (apart from things that were already fixed)?

I don't mean to defend MongoDB, i'm genuinely interested in finding a better NoSQL DB. I just usually get to hear the same "Fisher price" bashing without any real arguments.

[chris_wot]

The problem you have is that there are different types of NoSQL databases. Key value stores, document stores, graph databases, you name it they have their own specialty.

NoSQL's name shows just how nebulous the concept is. It was first coined by someone who built a relational database but without implementing SQL, then it was later used to describe distributed, non-relational databases that ignored, downgraded or discarded some form of ACID. Now it can be a retronym for "not only SQL".

In this space, work out what your actually needs are, then carefully research the technology and pick whatever is most appropriate.

[lucian1900]

It still has a global write lock, but now it's only global to the database.

[goldenkey]

I did not know this. That would be pretty awful for a high traffic service.

[lucian1900]

It is quite awful. You basically get a graph showing latency as almost directly proportional to number of concurrent requests :(

[mrmondo]

Not to mention it is not fun to admin.