Join processing for flash SSDs: remembering past lessons

Flash solid state drives (SSDs) provide an attractive alternative to traditional magnetic hard disk drives (HDDs) for DBMS applications. Naturally there is substantial interest in redesigning critical database internals, such as join algorithms, for flash SSDs. However, we must carefully consider the lessons that we have learnt from over three decades of designing and tuning algorithms for magnetic HDD-based systems, so that we continue to reuse techniques that worked for magnetic HDDs and also work with flash SSDs. The focus of this paper is on recalling some of these lessons in the context of ad hoc join algorithms. Based on an actual implementation of four common ad hoc join algorithms on both a magnetic HDD and a flash SSD, we show that many of the “surprising” results from magnetic HDD-based join methods also hold for flash SSDs. These results include the superiority of block nested loops join over sort-merge join and Grace hash join in many cases, and the benefits of bl...

• Type: Conference
• Year: 2009
• Where: DAMON
• Authors: Jaeyoung Do, Jignesh M. Patel
• Keywords: DAMON 2009, Hoc Join Algorithms, Informatics, Join Algorithms, flash Ssds