On Predictive Modeling for Optimizing Transaction Execution in Parallel OLTP Systems

TL;DR

This paper introduces a Markov model-based approach to optimize transaction execution in parallel OLTP systems by selecting suitable concurrency control, scheduling, and execution strategies, improving performance for diverse workloads.

Contribution

It presents a novel Markov model framework for automatic optimization of transaction execution strategies in parallel OLTP systems, addressing non-partitionable transactions.

Findings

Improved transaction throughput in diverse workloads

Effective selection of concurrency control schemes

Enhanced performance with speculative execution

Abstract

A new emerging class of parallel database management systems (DBMS) is designed to take advantage of the partitionable workloads of on-line transaction processing (OLTP) applications. Transactions in these systems are optimized to execute to completion on a single node in a shared-nothing cluster without needing to coordinate with other nodes or use expensive concurrency control measures. But some OLTP applications cannot be partitioned such that all of their transactions execute within a single-partition in this manner. These distributed transactions access data not stored within their local partitions and subsequently require more heavy-weight concurrency control protocols. Further difficulties arise when the transaction's execution properties, such as the number of partitions it may need to access or whether it will abort, are not known beforehand. The DBMS could mitigate these performance issues if it is provided with additional information about transactions. Thus, in this paper we present a Markov model-based approach for automatically selecting which optimizations a DBMS could use, namely (1) more efficient concurrency control schemes, (2) intelligent scheduling, (3) reduced undo logging, and (4) speculative execution. To evaluate our techniques, we implemented our models and integrated them into a parallel, main-memory OLTP DBMS to show that we can improve the performance of applications with diverse workloads.