Abstract: The invention is a system and method for database compression which creates partial indexing into compressed sub table blocks of databases. Table rows with the same or related indexing parameters are grouped as "sub-table blocks" and are stored as compressed binary objects, with the indexing fields stored in the same row, external to the binary block. The binary object expands to multiple database rows when accessed via the sub table block interface, thus forming a hierarchical, pre-joined database organization. Mechanisms are provided for creating, accessing, and manipulating the data blocks, and a date-based versioning mechanism. The compression employed is the known Vdelta package, which operates at a byte level to provide a useful compromise between speed and compression efficiency, even for relative short compression blocks. In realistic tests, the I/O time gained through compression results in a time saving which exceeds the processing penalty.