Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for operating on time sequences of data. In one aspect, a method includes a database management system storing and updating information in records in a table of a database, the records being associated with respective times that are spaced apart by time intervals, the database management system responding to a query that is phrased to imply a putative record with respect to a time interval that is not among the time intervals with which the records of the table are associated, and the response of the database management system to the query including a computation of a value of an attribute of the putative record from at least one non-null value of the attribute for one of the records of the table, the computation being based on an interpolation policy.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for a database designer and a database storage designer. In one aspect, a method includes creating a set of candidate projections and progressively narrowing the set of candidate projections and a set of queries by eliminating candidate projections that do not satisfy a performance improvement criterion for remaining queries based on the properties associated with the candidate projections.