图 书 馆
单音SPARQL查询的规范化Canonicalisation of Monotone SPARQL Queries |
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| 课程网址: | http://videolectures.net/iswc2018_salas_canonicalisation_sparql_q... |
| 主讲教师: | Jaime Salas |
| 开课单位: | 智利大学 |
| 开课时间: | 2018-11-22 |
| 课程语种: | 英语 |
| 中文简介: |  |
| 课程简介: | Caching in the context of expressive query languages such as SPARQL is complicated by the difficulty of detecting equivalent queries: deciding if two conjunctive queries are equivalent is npc, where adding further query features makes the problem undecidable. Despite this complexity, in this paper we propose an algorithm that performs syntactic canonicalisation of SPARQL queries such that the answers for the canonicalised query will not change versus the original. We can guarantee that the canonicalisation of two queries within a core fragment of SPARQL (monotone queries with select, project, join and union) is equal if and only if the two queries are equivalent; we also support other SPARQL features but with a weaker soundness guarantee: that the (partially) canonicalised query is equivalent to the input query. Despite the fact that canonicalisation must be harder than the equivalence problem, we show the algorithm to be practical for real-world queries taken from SPARQL endpoint logs, and further show that it detects more equivalent queries than when compared with purely syntactic methods. We also present the results of experiments over synthetic queries designed to stress-test the canonicalisation method, highlighting difficult cases. |
| 关 键 词: | SPARQL核心片段; 表达式查询语言; 规范化方法进行压力测试 |
| 课程来源: | 视频讲座网 |
| 数据采集: | 2022-12-20：cyh |
| 最后编审: | 2022-12-23：cyh |
| 阅读次数: | 43 |