Title :
Real-time index concurrency control
Author :
Haritsa, Jayant R. ; Seshadri, S.
Author_Institution :
Database Syst. Lab., Indian Inst. of Sci., Bangalore, India
Abstract :
Real time database systems are expected to rely heavily on indexes to speed up data access and thereby help more transactions meet their deadlines. Accordingly, high performance index concurrency control (ICC) protocols are required to prevent contention for the index from becoming a bottleneck. We develop real time variants of a representative set of classical B-tree ICC protocols and, using a detailed simulation model, compare their performance for real time transactions with firm deadlines. We also present and evaluate a real time ICC protocol called GUARD-link that augments the classical B-link protocol with a feedback based admission control mechanism. Both point and range queries, as well as the undos of the index action transactions are included in the study. The performance metrics used in evaluating the ICC protocols are the percentage of transactions that miss their deadlines and the fairness with respect to transaction type and size. Experimental results show that the performance characteristics of the real time version of an ICC protocol could be significantly different from the performance of the same protocol in a conventional (nonreal time) database system. In particular, B-link protocols, which are reputed to provide the best overall performance in conventional database systems, perform poorly under heavy real time loads. The new GUARD-link protocol, however, although based on the B-link approach, delivers the best performance (with respect to all performance metrics) for a variety of real time transaction workloads, by virtue of its admission control mechanism. GUARD-link provides close to ideal fairness in most environments
Keywords :
concurrency control; database indexing; protocols; real-time systems; transaction processing; tree data structures; trees (mathematics); B-link protocols; GUARD-link; ICC protocol; classical B-link protocol; classical B-tree ICC protocols; contention; data access; feedback based admission control mechanism; firm deadlines; heavy real time loads; high performance index concurrency control protocols; ideal fairness; index action transactions; nonreal time database system; performance characteristics; performance metrics; real time ICC protocol; real time database systems; real time index concurrency control; real time transaction workloads; real time transactions; real time variants; real time version; simulation model; transaction type; Access protocols; Admission control; Concurrency control; Database systems; Indexes; Measurement; Processor scheduling; Real time systems; Timing; Transaction databases;
Journal_Title :
Knowledge and Data Engineering, IEEE Transactions on