Read-only transactions in a distributed database

Abstract

A read-only transaction or query is a transaction which does not modify any data. Read-only transactions could be processed with general transaction processing algorithms, but in many cases it is more efficient to process read-only transactions with special algorithms which take advantage of the knowledge that the transaction only reads. This paper defines the various consistency and currency requirements that read-only transactions may have. The processing of the different classes of read-only transactions in a distributed database is discussed. The concept of R insularity is introduced to characterize both the read-only and update algorithms. Several simple update and read-only transaction processing algorithms are presented to illustrate how the query requirements and the update algorithms affect the read-only transaction processing algorithms.