Time-constrained query processing in CASE-DB

CASE-DB is a real-time, single-user, relational prototype DBMS that permits the specification of strict time constraints for relational algebra queries. Given a time constrained nonaggregate relational algebra query and a "fragment chain" for each relation involved in the query, CASE-DB initially obtains a response to a modified version of the query and then uses an "iterative query evaluation" technique to successively improve and evaluate the modified version of the query, CASE-DB controls the risk of overspending the time quota at each step using a "risk control technique".