An Adaptive Parallel Method for Indexing Transportation Moving Objects

Abstract

Transportation cyber-physical systems are constrained by spatiality and real-time because of their high level of heterogeneity. Therefore, applications like traffic control generally manage moving objects in a single-machine multithreaded manner, whereas suffering from frequent locking operations. To address this problem and improve the throughput of moving object databases, we propose a GPU-accelerated indexing method, based on a grid data structure, combined with quad-trees. We count object movements and decide whether a particular node should be split or be merged on the GPU. In this case, bottlenecked nodes can be translated to quad-tree without interfering with the CPU. Hence, waiting time of other threads caused by locking operations raised by object data updating can be reduced. The method is simple while more adaptive to scenarios where the distribution of moving objects is skewed. It also avoids shortcomings of existing methods with performance bottleneck on the hot area or spending plenty of calculation resources on structure balancing. Experiments suggest that our method shows higher throughput and lower response time than the existing indexing methods. The advantage is even more significant under the skewed distribution of moving objects.

Exploiting hashing for concurrent query processing and indexing of current location of moving objects

“…Many recent studies have proposed an index for moving objects and they involved parallelism to improve the response time of query operations. 8,[51][52][53][54][55][56][57][58][59] We have not included such studies in our scope as these studies are based on parallelism rather than concurrency control. And, focus of this article is on the resolution of conflicts while processing concurrent update and query operations.…”

“…U-Grid index 51,46,60 is based on a simple hash table with buckets holding the record. The grid cell hold by the object is mapped to a relevant bucket.…”

“…However, our focus is on designing of consistent index for moving objects not just a concurrency control algorithm. Many recent studies have proposed an index for moving objects and they involved parallelism to improve the response time of query operations 8,51–59 . We have not included such studies in our scope as these studies are based on parallelism rather than concurrency control.…”

“…Recently, hash table is utilized to effectively index moving objects 27,46,50,51 ; mitigating the limitations of computationally expensive split/merge operations in tree-based structures. However, the indices are proposed for single user environment and are not consistent.…”