Buffering in query evaluation over XML streams

2005 ◽  
Author(s):  
Ziv Bar-Yossef ◽  
Marcus Fontoura ◽  
Vanja Josifovski
Keyword(s):  
Query Evaluation ◽  
Xml Streams

scholarly journals Query Rewriting for Incremental Continuous Query Evaluation in HIFUN

Algorithms ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 149
Author(s):  
Petros Zervoudakis ◽  
Haridimos Kondylakis ◽  
Nicolas Spyratos ◽  
Dimitris Plexousakis
Keyword(s):  
Query Optimization ◽  
Query Language ◽  
Computational Cost ◽  
Continuous Queries ◽  
Continuous Query ◽  
Query Rewriting ◽  
Query Evaluation ◽  
Clear Separation ◽  
Complete Dataset ◽  
High Level

HIFUN is a high-level query language for expressing analytic queries of big datasets, offering a clear separation between the conceptual layer, where analytic queries are defined independently of the nature and location of data, and the physical layer, where queries are evaluated. In this paper, we present a methodology based on the HIFUN language, and the corresponding algorithms for the incremental evaluation of continuous queries. In essence, our approach is able to process the most recent data batch by exploiting already computed information, without requiring the evaluation of the query over the complete dataset. We present the generic algorithm which we translated to both SQL and MapReduce using SPARK; it implements various query rewriting methods. We demonstrate the effectiveness of our approach in temrs of query answering efficiency. Finally, we show that by exploiting the formal query rewriting methods of HIFUN, we can further reduce the computational cost, adding another layer of query optimization to our implementation.

GoFast: Graph-based optimization for efficient and scalable query evaluation

2021 ◽  
Vol 99 ◽  
pp. 101738
Author(s):  
Ishaq Zouaghi ◽  
Amin Mesmoudi ◽  
Jorge Galicia ◽  
Ladjel Bellatreche ◽  
Taoufik Aguili
Keyword(s):  
Query Evaluation
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