PHP 7 Programming Cookbook

Implementing object-relational mapping

There are two primary techniques to achieve a relational mapping between objects. The first technique involves pre-loading the related child objects into the parent object. The advantage to this approach is that it is easy to implement, and all parent-child information is immediately available. The disadvantage is that large amounts of memory are potentially consumed, and the performance curve is skewed.

The second technique is to embed a secondary lookup into the parent object. In this latter approach, when you need to access the child objects, you would run a getter that would perform the secondary lookup. The advantage of this approach is that performance demands are spread out throughout the request cycle, ...