1. In a data storage and retrieval system wherein data is stored and retrieved in pages, said data comprising connected nodes arranged such that each page stores only complete nodes, said connected nodes being connected via a plurality of overlapping tree structures, a method of minimizing page retrieval in the face of changing relationships between nodes comprising: selecting at least two of said overlapping tree structures; incrementally adjusting the association of nodes to pages dynamically based on data requests of a workload, separately according to each selected tree structure, to form modified pages for each tree structure, each modified paging partition being so as to reduce expected page faults; for each tree structure and associated modified paging partition calculating a modification gain to indicate which partition has provided a greater expected reduction of page faults; and selecting the tree structure and modified partition corresponding to a largest of said modification gains for continued data retrieval and for continued dynamic modification of said page node structure within said data storage and retrieval system.