# Efficient Multiway Hash Join on Reconfigurable Hardware

## TL;DR

This paper introduces algorithms for multiway hash joins on a new reconfigurable hardware accelerator called Plasticine, achieving significant speedups over CPUs and improving multiway join efficiency.

## Contribution

It presents novel algorithms for multiway joins on Plasticine hardware, demonstrating substantial performance improvements over traditional CPU implementations.

## Key findings

- 200X speedup over CPU for binary hash joins
- 3-way joins more efficient than cascaded binary joins by up to 45X on Plasticine
- Plasticine's high compute and communication bandwidth enable these gains

## Abstract

We propose the algorithms for performing multiway joins using a new type of coarse grain reconfigurable hardware accelerator~-- ``Plasticine''~-- that, compared with other accelerators, emphasizes high compute capability and high on-chip communication bandwidth. Joining three or more relations in a single step, i.e. multiway join, is efficient when the join of any two relations yields too large an intermediate relation. We show at least 200X speedup for a sequence of binary hash joins execution on Plasticine over CPU. We further show that in some realistic cases, a Plasticine-like accelerator can make 3-way joins more efficient than a cascade of binary hash joins on the same hardware, by a factor of up to 45X.