E-store

Abstract

On-line transaction processing (OLTP) database management systems (DBMSs) often serve time-varying workloads due to daily, weekly or seasonal fluctuations in demand, or because of rapid growth in demand due to a company's business success. In addition, many OLTP workloads are heavily skewed to "hot" tuples or ranges of tuples. For example, the majority of NYSE volume involves only 40 stocks. To deal with such fluctuations, an OLTP DBMS needs to be elastic; that is, it must be able to expand and contract resources in response to load fluctuations and dynamically balance load as hot tuples vary over time. This paper presents E-Store, an elastic partitioning framework for distributed OLTP DBMSs. It automatically scales resources in response to demand spikes, periodic events, and gradual changes in an application's workload. E-Store addresses localized bottlenecks through a two-tier data placement strategy: cold data is distributed in large chunks, while smaller ranges of hot tuples are assigned explicitly to individual nodes. This is in contrast to traditional single-tier hash and range partitioning strategies. Our experimental evaluation of E-Store shows the viability of our approach and its efficacy under variations in load across a cluster of machines. Compared to single-tier approaches, E-Store improves throughput by up to 130% while reducing latency by 80%.