Patent ID: 7424495
Filing Date: 2008-09-09
Classification: G06F,Y10S

Abstract:
1. A computer-implemented method of handling uniqueness constraints, said method comprising the computer-implemented steps of: storing a version history of each of a plurality of resources in a table, wherein the version history for each resource comprises a set of one or more values for said resource, wherein each value in the version history of a resource indicates the value that the resource had in a particular version of the resource; and in response to a request to perform an operation that causes a given resource that is subject to a uniqueness constraint to have a particular value, determining whether the uniqueness constraint is violated based on whether any version of any resource in said table other than said given resource has said particular value; wherein the uniqueness constraint is determined to be violated if any version of any resource in said table other than said given resource has said particular value; and wherein said uniqueness constraint is not violated by existence of a version of said given resource in said table that has said particular value; wherein, after performance of said operation, said table comprises multiple occurrences of a particular value in a column that is subject to said uniqueness constraint.