Gonzalo Ayuso has a new post to his blog today with the results of some performance analysis he ran when fetching data with PHP and PDO.

Fetching data from databases is a common operation in our work as developers. There are many drivers (normally I use PDO), but the usage of all of them are similar and switch from one to another is not difficult (they almost share the same interface). In this post I will focus on fetching data.

He includes his sample scripts - one using just fetch() and the other using fetchAll() - that include some timing and memory checking logic and includes the results of his "limit 10000" queries from his tables. Not surprisingly, the fetchAll required more memory than the fetch call. Event changing it to a loop of fetch() methods results in about the same amount of memory as a fetchAll.