## IIT Database Group

### Abstract

Snapshot semantics is widely used for evaluating queries over temporal data: temporal relations are seen as sequences of snapshot relations, and queries are evaluated at each snapshot. In this work, we demonstrate that current approaches for snapshot semantics over interval-timestamped multiset relations are subject to two bugs regarding snapshot aggregation and bag difference. We introduce a novel temporal data model based on K-relations that overcomes these bugs and prove it to correctly encode snapshot semantics. Furthermore, we present an efficient implementation of our model as a database middleware and demonstrate experimentally that our approach is competitive with native implementations.

### bibtex

@article{DG19,
author = {Dign\"{o}s, Anton and Glavic, Boris and Niu, Xing and B\"{o}hlen, Michael H. and Gamper, Johann},
journal = {Proceedings of the VLDB Endowment},
keywords = {Temporal Databases; Annotations},
longversionurl = {https://arxiv.org/pdf/1902.04938},
projects = {Snapshot Semantics for Temporal Databases},
number = {6},
pages = {639--652},
pdfurl = {http://www.vldb.org/pvldb/vol12/p639-dignoes.pdf},
title = {{Snapshot Semantics for Temporal Multiset Relations}},
venueshort = {PVLDB},
volume = {12},
year = {2019}
}


### Reference

Snapshot Semantics for Temporal Multiset Relations Anton Dignös, Boris Glavic, Xing Niu, Michael H. Böhlen and Johann Gamper Proceedings of the VLDB Endowment. 12, 6 (2019) , 639–652.