Tips and troubleshooting for precedence rules

The creation of dimensions can be facilitated with precedence rules. Consider the task of creating a Geography dimension as a hierarchy of country, state, and city. The hierarchy would need to be created manually, with Country as the root dimension value. Each country dimension value would have its corresponding states as children and each state its corresponding cities. In this scenario, the onus is on the knowledge worker to create and maintain this potentially enormous hierarchy.

Precedence rules offer a much simpler solution. The knowledge worker can produce the same results by creating three individual dimensions-Country, State, and City-and configuring precedence rules such that the State dimension isn't presented until a country has been chosen and the City dimension isn't presented until a state has been chosen. Each dimension is flat and can be auto-generated, so this solution involves much less initial and maintenance effort. Clearly, creating the hierarchy by hand is a much more difficult task than auto-generating the three dimensions, configuring precedence rules and letting contraction do the work to give the application the desired behavior (that is, to mimic the hierarchy).