Be aggregate aware

摘要

Recent releases of several major database engines have included optimizers that are "aggregate-aware." That is, the optimizer can be made aware of pre-computed aggregates stored in the database and exploit them to reduce query time and cost. It'simportant to be aware that, although exploiting this feature might sound unequivocally like a good idea, you must apply these engines' capabilities to suit your particular situation - lest you increase your troubles rather than relieve them.