Processing queries for first-few answers
Roberto J. Bayardo, Daniel P. Miranker · 1996
Special support for quickly finding the first-few answers of a query is atready appearing in commercial database systems.This support is useful in active databases,when dealing with potentially unmanageable query results, and as a declarative akernativeto navigational techniques.In this paper, wediscuss query processing techniques for first-answer queries.We provide a method for predicting the cost of a first-answer query plan under an execution model that attempts to reduce wasted effort in join pipelining.We define new statistics necessary for accurate cost prediction, and discuss techniques for obtaining the statistics through traditional statistical measures (e.g.selectivity) and semantic data properties commonly specified through modem 00DB and relatiorud schemas.The proposed techniques also apply to all-answer query processing when optimizing for fast delivery of the initiat query results.