Performance impact from enabling the display of disabled refinements falls into three categories. They are discussed in the order of importance.
The cost of computation involved in determining the base and default navigation states.
The base and default navigation states are computed based on the top-level filters that may belong to these states. These filters are text searches, range, EQL and record filters and selections from dimensions. The types and numbers of these top-level filters in the base and default navigation states affect the MDEX Engine processing involved in computing the default navigation state. The more filters exist in the current navigation state, the more expensive is the task; some filters, such as EQL, are more expensive to take into account than others.
The trade off between using dynamic refinement ranking and disabled refinements.
In general, these two features pursue the opposite goals in the user interface — dynamic ranking enables you to intelligently return less information to the users based on most popular dimension values, whereas disabled refinements let you return more information to the users based on those refinements that are not available in the current navigation state but would have been available if some of the selections were not made by the users.
Therefore, carefully consider your choices for the user interface of your front-end application and decide for which of your refinements you would like to have one of these user experiences:
If, for example, for some dimensions you want to have only the most popular dimension values returned, you need dynamic ranking for those refinements. For it, you set the sampling size of records (with
--esampin), which directly affects performance: the smaller the sampling, the quicker the computation. However, for those dimensions, the MDEX Engine then does not compute (and therefore, does not return) disabled refinements.If, on the other hand, in your user experience you would like to show grayed out (disabled) refinements, and your performance allows it, you can decide to enable them, instead of dynamic ranking for those dimensions. This means that for those dimensions, you need to disable dynamic ranking. As a side effect, this involves a performance cost, since computing refinements without dynamic ranking is more expensive. In addition, with dynamic ranking disabled, the MDEX Engine will need to compute refinement counts for more dimension values.
The cost of navigation queries.
Disabled refinements computation slightly increases the navigation portion of your query processing. This increase is roughly proportional to the number of dimensions for which you request the MDEX Engine to return disabled refinements.
