Unified fine-granularity buffering of index and data: approach and implementation

Disk I/O is recognized as a major performance bottleneck in many database applications. Consequently, a topic of considerable study in database systems has traditionally been buffer management. Recently, disk pages have been increasing in size, enabling more and more data to fit in a single page. Such a trend suggests that buffering the data at a grain size finer than a page may use memory better. As a result, there has been some interest in fine-granularity buffering. Past approaches to fine-granularity buffering have proposed buffering either data tuples alone or index entries alone. In this paper, we propose a scheme to support fine-granularity buffering of both index and data entries in a unified manner. The scheme, which we call Hot-Entry buffering, can be used in combination with conventional page-level buffering. Through the experimental evaluation of a simple system, we demonstrate the benefits of our scheme over conventional page-level buffering, and over index-only and data-only fine-granularity buffering. In particular, we show that, for a range of parameter values, our buffering scheme speeds-up query execution by 20-60% relative to page-level buffering only, and by 10-20% relative to the best of index-only or data-only fine-granularity buffering.