27. An article of manufacture having computer-readable program portions embedded thereon for accessing data in a record-based data storage system in response to a join query, the program portions comprising instructions for: searching documents and storing join mappings, the join mappings mapping join keys to documents and join key values to the documents; using an index, returning primary and secondary result sets for primary and secondary queries of the join query; using the join mappings, identifying documents from the primary result sets and the secondary result sets that have common field values; retrieving at least a subset of the identified documents from the primary result sets and the secondary result sets that have common field values.
35. The article of manufacture of claim 27 wherein the program portions further comprise instructions for: determining if sufficient volatile memory is available to store the join mappings; if sufficient memory exists, storing the join mapping in volatile memory; and if sufficient memory does not exist, deleting existing join mappings and storing the join mapping.