Tiered Sampling: An Efficient Method for Counting Sparse Motifs in Massive Graph Streams
Tiered Sampling: An Efficient Method for Counting Sparse Motifs in Massive Graph Streams
复制标题
分层采样:一种计算海量图流中稀疏图案的有效方法
DOI:
10.1145/3441299
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发表时间:
2021
影响因子:
3.6
通讯作者:
Upfal, Eli
中科院分区:
文献类型:
--
作者:
Stefani, Lorenzo De;Terolli, Erisa;Upfal, Eli
We introduceTiered Sampling, a novel technique for estimating the count of sparse motifs in massive graphs whose edges are observed in a stream. Our technique requires only a single pass on the data and uses a memory of fixed sizeM, which can be magnitudes smaller than the number of edges.Our methods address the challenging task of counting sparse motifs—sub-graph patterns—that have a low probability of appearing in a sample ofMedges in the graph, which is the maximum amount of data available to the algorithms in each step. To obtain an unbiased and low variance estimate of the count, we partition the available memory into tiers (layers) of reservoir samples. While the base layer is a standard reservoir sample of edges, other layers are reservoir samples of sub-structures of the desired motif. By storing more frequent sub-structures of the motif, we increase the probability of detecting an occurrence of the sparse motif we are counting, thus decreasing the variance and error of the estimate.While we focus on the designing and analysis of algorithms for counting 4-cliques, we present a method which allows generalizingTiered Samplingto obtain high-quality estimates for the number of occurrence of any sub-graph of interest, while reducing the analysis effort due to specific properties of the pattern of interest.We present a complete analytical analysis and extensive experimental evaluation of our proposed method using both synthetic and real-world data. Our results demonstrate the advantage of our method in obtaining high-quality approximations for the number of 4 and 5-cliques for large graphs using a very limited amount of memory, significantly outperforming the single edge sample approach for counting sparse motifs in large scale graphs.