关键词: 时态索引, 时态数据, 分布式, 时态聚合, 计数排序

Abstract: Abstract: In the era of big data and cloud computing, querying and analyzing temporal big data faces many important challenges. Focused on the issues such as poor query performance and ineffective utilization of indexes for temporal aggregation range query among them, a distributed temporal index for temporal aggregation range query was proposed. Firstly, random or Round-Robin strategy was used to partition the temporal data. Secondly, intra-partition index construction algorithm based on timestamp’s bit array prefix was used to build intra-partition index, and partition statistics including time span were recorded. Thirdly, data partitions whose time span overlaps with the query time interval were selected by predicate pushdown operation, and were pre-aggregated by index scan. Finally, all pre-aggregated values obtained from each partition were merged and aggregated by time. The simulation results show that the execution time of intra-partition index construction algorithm of the index is similar for processing data with densities of 2400 entries per unit of time and 0.001 entries per unit of time. Compared to ParTime, temporal aggregation range query algorithm of the index takes at least 22% less time for each step when querying the data in the first 75% of timeline and at least 11% less time for each step when executing selective aggregation. Therefore, the index is fast in most temporal aggregate range query tasks and its intra-partition index construction algorithm is capable to solve data sparsity and performs efficiently.

Key words: temporal index, temporal data, distributed, temporal aggregation, counting sort