Why is it not desirable to force users to make an explicit choice of a query processing strategy? Are there cases where it is desirable for users to be aware of the costs of competing query-processing strategies? Please explain.© BrainMass Inc. brainmass.com December 20, 2018, 9:37 am ad1c9bdddf
The basic ingredients of the query decomposition are
(1) To discover pieces of a query which are joined to the remainder by a single joining variable
(2) To substitute for a variable. The overall strategy is to break up a query at the joining variables whereever possible, and to select a variable for substitution, which incurs a "cost" wherever substitution can no longer be ignored.
For simple queries, elaborate optimization may well do more harm ...
The expert examines query processing strategies.