Accession Number : ADA242682


Title :   The Design and Implementation of the Ariel Active Database Rule System


Descriptive Note : Final rept. Sep 88-Sep 91,


Corporate Author : WRIGHT LAB WRIGHT-PATTERSON AFB OH


Personal Author(s) : Hanson, Eric N ; Baker, William R


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a242682.pdf


Report Date : Oct 1991


Pagination or Media Count : 48


Abstract : This paper describes the design and implementation of the Ariel DBMS and it's tightly-coupled forward-chaining rule system. The query language of Ariel is a subset of POSTQUEL, extended with a new production-rule sublanguage. Ariel supports traditional relational database query and update operations efficiently, using a System R-like query processing strategy. In addition, the Ariel rule system is tightly coupled with query and update processing. Ariel rules can have conditions based on a mix of patterns, events, and transitions. For testing rule conditions, Ariel makes use of a discrimination network composed of a special data structure for testing single-relation selection conditions efficiently, and a modified version of the TREAT algorithm, called A- TREAT, for testing join conditions. The key modification to TREAT (which could also be used in the Rete algorithm) is the use of virtual a-memory nodes which save storage since they contain only the predicate associated with the memory node instead of copies of data matching the predicate. The rule-action executor in Ariel binds the data matching a rule's condition to the action of the rule at rule fire time, and executes the rule action using the query processor.


Descriptors :   *DATA BASES , NETWORKS , MODIFICATION , MATCHING , MEMORY DEVICES , STORAGE , DISCRIMINATION , ALGORITHMS , NODES


Subject Categories : Computer Systems


Distribution Statement : APPROVED FOR PUBLIC RELEASE