Query-sensitive graph partitioner for pattern matching applications

Abstract

Searching and mining in large graphs is critical to a variety of applications, at the core of which is the pattern matching activity. The scalable processing of large graphs requires careful distribution of graphs across clusters. Graph partitioning is the technique that divides a big graph into several non-overlapped subgraphs and assigns each subgraph to a compute node. Traditional workload agnostic partitioners aim to minimize the number of inter-partition edges using only graph topology, which, however, may not obtain the best solution if the workload exhibits skew. Some workload-aware partitioners choose to mine information from a specific workload and use it to minimize the number of inter-partition traversals during execution; however, their methods are not suitable for pattern matching applications. In this work, we propose a query-sensitive graph partitioner that aims to improve existing partitioning for a given pattern matching workload. The partitioner takes any initial partitioning as a starting point and iteratively adjusts it by exchanging chosen clusters across partitions, heuristically reducing the probability of inter-partition traversals. We determine a few implementation-irrelative factors that may increase the traversal probability of an edge and quantify them into a calculable indicator with information from query patterns and graph topology. Then, we propose an efficient algorithm to calculate the indicator and implement a graph repartitioner by combining the indicator with a greedy cluster-exchanging mechanism. Finally, we generate a large heterogeneous labeled graph with real-world data crawled from the Netease Music website and evaluate the partitioning quality of our repartitioner with a few meaningful query patterns of common topologies including line, loop and branching. Compared with a hash-based partitioning, our system can reduce the inter-partition traversals by at least 70%. Compared with the state-of-the-art graph partitioner Metis, our repartitioner can reduce the inter-partition traversals by at least 50%.