Patent ID: 7376639

Claim:
Computer-based method implemented in a query optimizer to incorporate partial information about multivariate distributions in a constrained optimization form, said method comprising the steps of: modeling one or more multivariate distributions based on available statistical information in a probability space; modeling one or more multivariate distributions for which no statistical information is available via a constrained optimization approach and entropy maximization over said probability space, said constrained optimization approach further comprises the steps of: defining a selectivity, x b , associated with each atom, ^ i∈N p i b i , for b i ∈{0,1}, each atom representing a term in disjunctive normal form (DNF) over a predicate space of n predicates p i ; forming a plurality of constraints based on known selectivities; and computing a solution for all atoms x b , b i ∈{0,1} that maximizes entropy while minimizing the function ∑ b ∈ { 0 , 1 } n ⁢ x b ⁢ log ⁢ ⁢ x b and satisfying said plurality of constraints, and said query optimizer using all available statistical information and both of said modeled distributions during cardinality estimation.