1. In a computing environment in which source data is arranged as a data structure comprising record identifiers and dimensions, each dimension having a data value, which may be non-null or null for each record identifier, a method comprising, constructing an inverted index corresponding to a dimension, including by mapping data from raw dimension values to mapped values based on mapping entries in a dimension table, and arranging the record identifiers into subgroups within an record identifier data structure based on each record identifier's corresponding mapped value in the dimension table.