Storage and Serialization Data Modeling Important section.
Every abstraction hides a complexity of the layer below. Our modeling will need to go to the lowest layer possible to find the best optimization.
Impedance Mismatch The disconnect between models of two layers.
Locality Fewer seeks/joins and compression options, but more memory used (disk and main).
The answer to any specific question, like what is the right level of denormalization, is “depends on the business question.