Multidimensional data space queries with expression evaluation

摘要

A system and techniques for executing queries of a sparse multidimensional data space in the presence of expressions. A dimension is associated with a set of data references, which reference stored data items. A query expression has dimension or a data reference as an operand. A result space with one or more result dimensions is defined based on the query. A plan is built and executed for retrieving the stored data items associated with the result dimensions, and forming “calculated data items” by evaluating the expression. Executing the plan produces a stream of data tuples, each having a set of data components storing the retrieved data items and/or the calculated data items. Data components are either empty or have data values. An iterative algorithm is employed on the stream to locate the data tuples that are empty at the intersection of each result dimension.