Objects of this class provide a means of reading in compound records. A compound record is a parent record along with a set of zero or more child records. It may also be an orphan child record. This class builds compound records from a set of record sources. One source represents the parent table, zero or more additional sources represent the child tables. Each source is associated with a table name, all table names must be unique.

To build compound records it is assumed that all sources are sorted by the parent record key. The child record sources are not sorted by their own key, they must be sorted by the parent record key. In this way the sources can be read in parallel and merged.