[mfenniak]

I think the advice in point #1 only makes sense with a caveat: When performance is an issue, if you can calculate or process it at the application layer _without adding load to the database layer_, then take it out of the database layer.

For example, order-by w/ limit/offset? If you do that at the application layer, you've increased the I/O usage on the database server, and clearly this advice doesn't make sense.

On the other hand, group-by (assuming no HAVING)? If you do that at the application layer, you've reduced the load on the database server, increased the load on the network, and you've probably made a justifiable performance vs. scalability trade-off. If you measure it and back it up with data.

I think the advice here in the article is too broad, but I can see a kernel of wisdom in it that is non-intuitive.

[markokocic]

Well, without a caveat the advice is plain wrong in 99% cases, since that caveat changes the advice completely.