Section 5.10. Holy Simplicity

5.10. Holy Simplicity

It is reasonable and safe to assume that any storage option that is not the default one, however attractive it may look, can introduce a degree of complexity out of all proportion to the possible gains that may (or may not) be achieved. In the worst case, a poorly chosen storage option can dramatically degrade performance. Military history is full of impregnable fortresses built in completely the wrong places that failed to fill any useful purpose, and of many a Great Wall that never prevented any invasion because the enemy, a bad sport, failed to behave as planned. All organizations undergo changes, such as divisions and mergers. Business plans and processes may change, too. Careful plans may have to be scrapped and rebuilt from scratch.

The trouble with structuring data in a particular way is that it is often done with a particular type of process in mind. One of the beauties of the relational model is its flexibility. By strongly structuring your data at the physical level, you may sacrifice, in a somewhat hidden way, some of this flexibility. Of course, some structures are less constraining than others, and data partitioning is almost unavoidable with enormous databases. But always test very carefully and keep in mind that changing the physical structure of a big database because it was poorly done initially can take days, if not weeks, to complete.

The physical storage organization that works for us today may work against us tomorrow.