Python Cookbook

Chapter 8. Databases and Persistence

Introduction

Credit: Aaron Watters, CTO, ReportLab

There are three kinds of people in this world: those who can count and those who can’t.

However, there are only two kinds of computer programs: toy programs and programs that interact with persistent databases of some kind. That is to say, most real computer programs must retrieve stored information and record information for future use. These days, this is true of almost every computer game, which can typically save and restore the state of the game at any time. So when I refer to toy programs, I mean programs written as exercises, or for the fun of programming. Nearly all real programs (such as programs that people get paid to write) have some persistent database storage/retrieval component.

When I was a Fortran programmer in the 1980s I noticed that although almost every program had to retrieve and store information, they almost always did it using home-grown methods. Furthermore, since the storage and retrieval part of the program was the least interesting component from the programmer’s point of view, these parts of the program were frequently implemented very sloppily and were hideous sources of intractable bugs. This repeated observation convinced me that the study and implementation of database systems sat at the core of programming pragmatics, and that the state of the art as I saw it then required much improvement.

Later, in graduate school, I was delighted to find that there was an impressive ...