Query Processing in Constraint-Based Database Caches

Database caching uses full-fledged DBMSs as caches to adaptively maintain sets of records from a remote DB and to evaluate queries on them, whereas Web caching keeps single Web objects ready somewhere in caches in the user-to-server path. Using DB caching, we are able to perform declarative and setoriented query processing nearby the application, although data storage and consistency maintenance is remote. We explore which query types can be supported by DBMS-controlled caches whose contents are constructed using parameterized cache constraints. Schemes on single cache tables or on cache groups correctly perform local evaluation of query predicates. In practical applications, only safe schemes guaranteeing recursion-free load operations are acceptable. Finally, we comment on future application scenarios and research problems including empirical performance evaluation of DB caching schemes.