DaC-Join: A join operator for improving database performance on modern hardware

摘要

The computer industry is moving toward the construction in large scale of chips with hundredsof cores to increase on-chip parallelism. In parallel, computers with solid state memory, theso-called solid state drive (SSD for short), providing petabytes of storage area, is emerging.Nonetheless, database systems (DBSs) were designed based upon two premises. The first isthe usage of magnetic disks (HDDs). The second one is that distributed DBSs could scalebeyond what a single-node DBMS can support. However, the latter premise only holds for asmall number of CPU cores per node and for a limited number of nodes. Thus, to fully exploitbenefits of parallelism and high IOPS rates supported by many-core machines with SSDs,database systems should be aware of upcoming CPU architecture and storage technology. Inthis paper, we present a new join algorithm, denoted DaC-Join, whose key goal is to exploiton-chip parallelism and high IOPS rates delivered by modern hardware. DaC-Join is able to runon multiple cores in parallel, increasing this way intra-operator parallelism. Furthermore, theproposed operator effectively decreases the activity of writing back join temporary results onSSDs, which minimizes the problem of write operation latency in SSDs. In order to validate thenovel approach, simulations with a prototype have been conducted over TPC-H benchmarkdatabase, scale factor 10. The achieved results evidence the suitability of DaC-Join.