14. The method of claim 13 , wherein: the first set of formulas includes a first formula and the rewritten set of formulas does not include a first formula; and the step of rewriting includes pruning said first formula from said first set of formulas.
16. The method of claim 14 , wherein: each formula of said first set of formulas: evaluates one or more cells in said array, and modifies as one or more cells in said array a measure column in said relation; the step of rewriting is based on a set of conditions for a given formula of said first set of formulas that include a first condition, a second condition, and a third condition, wherein: (1) the first condition is that one or more cells modified by the given formula of said first set of formulas are not evaluated by any other formula of said first set of formulas, (2) the second condition is that the one or more cells modified by the given formula are filtered out by said one or more predicates, and (3) the third condition is that the measure column is not referenced by said first query; the step of rewriting includes: (A) establishing a first subset of said first set of formulas that meet the first condition; (B) for each formula of said first subset, pruning said each formula from said first set of formulas if said each formula meets either the second condition or the third condition; (C) after performing step (B), establishing a second subset of the remaining formulas in said first set of formulas that meet the first condition.