VAQUERO: A Scratchpad-based Vector Accelerator for Query Processing.

Database Management Systems (DBMS) have become an essential tool for industry and research and are often a significant component of data centers. There have been many efforts to accelerate DBMS application performance. One of the most explored techniques is the use of vector processing. Unfortunately, conventional vector architectures have not been able to exploit the full potential of DBMS acceleration. In this paper, we present VAQUERO, our Scratchpad-based Vector Accelerator for QUEry pROcessing. VAQUERO improves the efficiency of vector architectures for DBMS operations such as data aggregation and hash joins featuring lookup tables. Lookup tables are significant contributors to the performance bottlenecks in DBMS processing suffering from insufficient ISA support in the form of scatter-gather instructions. VAQUERO introduces a novel Advanced Scratchpad Memory specifically designed with two mapping modes - direct- and associative-mode. These mapping modes enable VAQUERO to accelerate real-world databases with workload sizes that significantly exceed the scratchpad memory capacity. Additionally, the associative-mode allows to use VAQUERO with DBMS operators that use hashed keys, e.g. hash-join and hash-aggregate. VAQUERO has been designed considering general DBMS algorithm requirements instead of being based on a particular database organization. For this reason, VAQUERO is capable to accelerate DBMS operators for both row- and column-oriented databases. In this paper, we evaluate the efficiency of VAQUERO using two highly optimized popular open-source DBMS, namely the row-based PostgreSQL and column-based MonetDB. We implemented VAQUERO at the RTL level and prototype it, by performing Place&Route, at the 7nm technology node. VAQUERO incurs a modest 0.15% area overhead compared with an Intel Ice Lake processor. Our evaluation shows that VAQUERO significantly outperforms PostgreSQL and MonetDB by 2.09x and 3.32x respectively, when processing operators and queries from the TPC-H benchmark.