DSM vs. NSM: CPU Performance Tradeoffs in Block-Oriented Query Processing

Abstract

Comparisons between the merits of row-wise storage (NSM) \nand columnar storage (DSM) are typically made with respect \nto the persistent storage layer of database systems. In \nthis paper, however, we focus on the CPU efficiency tradeoffs \nof tuple representations inside the query execution engine, \nwhile tuples flow through a processing pipeline. We \nanalyze the performance in the context of query engines using \nso-called "block-oriented" processing --- a recently popularized \ntechnique that can strongly improve the CPU efficiency. \nWith this high efficiency, the performance trade-offs \nbetween NSM and DSM can have a decisive impact on the \nquery execution performance, as we demonstrate using both \nmicrobenchmarks and TPC-H query 1. This means that \nNSM-based database systems can sometimes benefit from \nconverting tuples into DSM on-the-fly, and vice versa. \