The Art of SQL

Chapter 5. Terrain

Understanding Physical Implementation

[...] haben Gegend und Boden eine sehr nahe [...] Beziehung zur kriegerischen Tätigkeit, nämlich einen sehr entscheidenden Einfluß auf das Gefecht.

[...] Country and ground bear a most intimate [...] relation to the business of war, which is their decisive influence on the battle.

—Carl von Clausewitz (1780-1831) Vom Kriege, V, 17

What a program sees as a table is not always the plain table it may look like. Sometimes it’s a view, and sometimes it really is a table, but with storage parameters that have been very carefully established to optimize certain types of operations. In this chapter, I explore different ways to arrange the data in a table and the operations that those arrangements facilitate.

I should emphasize from the start that the topic of this chapter is not disk layout, nor even the relative placement of journal and data files. These are the kinds of subjects that usually send system engineers and database administrators into mouth-watering paroxysms of delight—but no one else. There is much more to database organization than the physical dispersion of bytes on permanent storage. It is the actual nature of the data that dictates the most important choices.

Both system engineers and database administrators know how much storage is used, and they know the various possibilities available in terms of data containers, whether very low-level data containers such as disk stripes or high-level data containers such as tables. ...