Change area B-trees: A technique to aid error recovery
Jonathan Michael Mullin · The Computer Journal · 1981
B-tree structures with the restriction that all data records are stored at the leaves of the tree are investigated from the standpoint of recovery from hardware and software errors. A technique is presented for maintaining the original file inviolate—which could reside on read only memory—and recording changes in a separate area. Standard algorithms are used for direct access search and hence retrieval time is not affected. Update algorithms are slightly altered to direct all modifications to a separate area. Expressions are developed for storage and time penalties. Due to system overheads, the range of application is limited to files which can tolerate small blocking factors. The technique is contrasted to differential files and a direct point comparison is made to an earlier paper by Severance and Lohman.