[wuliwong]

They are overstated the naivety of the "naive" approach.

The article states:

'directly fetch all the photos that the user followed from a single, monolithic data store, sort them by creation time and then only display the latest 10'

That isn't how the query would work. It is implying that the query would return all the results, clearly it would only return 10. I haven't read all the details, I'm sure Instagram does something better then this basic SQL now but it is silly in a technical article to overstate the problem in such an obviously incorrect way.