Similarity Group-By operators for multi-dimensional relational data

Mingjie Tang, Ruby Y. Tahboub, Walid G. Aref, Mikhail J. Atallah, Qutaibah M. Malluhi, Mourad Ouzzani, Yasin N. Silva
2016 2016 IEEE 32nd International Conference on Data Engineering (ICDE)  
The SQL group-by operator plays an important role in summarizing and aggregating large datasets in a data analytics stack. While the standard group-by operator, which is based on equality, is useful in several applications, allowing similarityaware grouping provides a more realistic view on real-world data that coud lead to better insights. The Similarity SQL-based Group-By operator (SGB, for short) extends the semantics of the standard SQL Group-by by grouping data with similar but not
more » ... ily equal values. While existing similarity-based grouping operators efficiently materialize this "approximate" semantics, they primarily focus on one-dimensional attributes and treat multi-dimensional attributes independently. However, correlated attributes, such as in spatial data, are processed independently, and hence, groups in the multi-dimensional space are not detected properly. To address this problem, we introduce two new SGB operators for multi-dimensional data. The first operator is the clique (or distance-to-all) SGB, where all the tuples in a group are within some distance from each other. The second operator is the distance-to-any SGB, where a tuple belongs to a group if the tuple is within some distance from any other tuple in the group. Since a tuple may satisfy the membership criterion of multiple groups, we introduce three different semantics to deal with such a case: (i) eliminate the tuple, (ii) put the tuple in any one group, and (iii) create a new group for this tuple. We implement and test the new SGB operators and their algorithms inside PostgreSQL. The overhead introduced by these operators proves to be minimal and the execution times are comparable to those of the standard Group-by. The experimental study, based on TPC-H and a social check-in data, demonstrates that the proposed algorithms can achieve up to three orders of magnitude enhancement in peformance over baseline methods developed to solve the same problem. Index Terms-similarity query, relational database, ! • M. Tang and R. Tahboub is with the
doi:10.1109/icde.2016.7498368 dblp:conf/icde/TangTAAMOS16 fatcat:qljocraeajg67hguptblyc7vma