1. A computer-based method to perform query optimization by automatically finding and exploiting hidden, fuzzy algebraic constraints in a database, said method comprising the steps of: (a) constructing one or more candidates of form C=(a 1 , a 2 , P, ⊕), wherein a 1 and a 2 are numerical attributes associated with column values of data in said database, P is a pairing rule, and ⊕ is any of the following algebraic operators: +, −, ×, or /; (b) constructing, for each candidate identified in (a), an algebraic constraint AC=(a 1 , a 2 , P, ⊕, I 1 ,. .. , I k ) by applying any of, or a combination of the following techniques to a sample of column values: statistical histogramming, segmentation, or clustering, where I 1 ,. .. , I k is a set of disjoint intervals and k≧1, and wherein said constructed algebraic constraints are used in query optimization.