1. A method of creating a database abstraction model over an underlying physical database, comprising: defining a plurality of logical fields, wherein each logical field specifies at least an access method mapping the logical field to data in the underlying physical database, and wherein at least one logical field includes timeline metadata indicating where data elements retrieved for the logical field occur on a timeline; and providing an abstract query building interface used to compose an abstract query from the plurality of logical fields, wherein the abstract query specifies (i) a set of conditional expressions, wherein each conditional expression includes a logical field, a conditional operator, and a comparison value, and wherein at least one conditional operator specifies a temporal operator relating the logical field and comparison value, and (ii) a set of logical fields used to retrieve a set of query results that are consistent with the set of conditions.