Parallelization of XPath Queries Using Modern XQuery Processors

Abstract

A practical and promising approach to parallelizing XPath queries was proposed by Bordawekar et al. in 2009, which enables parallelization on top of existing XML database engines. Although they experimentally demonstrated the speedup by their approach, their practice has already been out of date because the software environment has largely changed with the capability of XQuery processing. In this work, we implement their approach in two ways on top of a state-of-the-art XML database engine and experimentally demonstrate that our implementations can bring significant speedup on a commodity server.

Pipelined XPath Query Based on Cost Optimization

“…Reference [11] further introduces a cost estimation model to guide the partitioning work to support the automatic generation of parallel query plans. After that, Sato et al [5] carried out XPath parallelization research on the new XML query platform BaseX [12] on the basis of Bordawekar's work. In the previous work [4], we proposed an efficient XPath evaluation method pM 2 based on relation matrix.…”

“…e parallel XPath query technology for multicore computing has been developed in recent years. From the perspective of the parallel pattern, the implementation technology of XPath parallelization includes data parallelism [3][4][5], task parallelism [6], and pipeline parallelism [7].…”

“…In Algorithm 3, firstly, according to the number of query primitives, local blocking queues (lines 1 and 2) are created, and then the execution body is defined, which processes the calls of pipelined query primitives in a nested iterative manner (lines [4][5][6][7][8][9][10][11][12][13][14][15]. When processing the first primitive in a stage, if the end flag of execution is detected, the flag will be passed to the following pipeline stage, and then the iteration operation in the execution body will be immediately exited (lines 6-8).…”