DB design and optimization considerations for a social application

Question

The usual case. I have a simple app that will allow people to upload photos and follow other people. As a result, every user will have something like a \"wall\" or an \"activity

Answer 1

I'm reading more and more about NoSQL solutions and people suggesting them, however no one ever mentions drawbacks of such choice. Most obvious for me is lack of transactions - imagine if you lost a few records every now and then (there are cases reporting this happens often).

But, what I'm surprised with is that no one mentions MySQL being used as NoSQL - here's a link for some reading.

In the end, no matter what solution you choose (relational database or NoSQL storage), they scale in similar manner - by sharding data across network (naturally, there are more choices but this is the most obvious one). Since NoSQL does less work (no SQL layer so CPU cycles aren't wasted on interpreting SQL), it's faster, but it can hit the roof too.

As Elad already pointed out - building an app that's scalable from the get go is a painful process. It's better that you spend time focusing on making it popular and then scale it out.