OVI-3 : A NoSQL visual query system supporting efficient anti-joins

Sami El-Mahgary*, Eljas Soisalon-Soininen, Pekka Orponen, Petri Rönnholm, Hannu Hyyppä

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

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The aim of this work was to develop a technique to speed up complex joins in an incremental visual query system. When designing a visual, highly interactive interface for ad-hoc (read-only) queries, fast response times are of paramount importance. While a column-oriented DBMS reduces the inherent latency found in relational DBMS, there is still the question of how to index the data, especially so as to support complex joins. Equi-joins that involve a many-to-many relationship are an example of complex joins that arise frequently and whose efficient processing is essential for fast query processing. We present OVI-3, a NoSQL visual query system based on incremental querying that uses a simple directory-based indexing scheme for faster processing of such complex joins. The system has been piloted using real data from a student database at Aalto University. The results demonstrated that for certain complex joins the presented indexing scheme outperforms SQL queries from a data server, especially for queries involving anti-joins (negation), where OVI-3 provided an orders of magnitude speed improvement.

Original languageEnglish
Pages (from-to)777–801
Number of pages25
Issue number3
Early online date21 Sept 2022
Publication statusPublished - Jun 2023
MoE publication typeA1 Journal article-refereed


  • Incremental query
  • Joins
  • NoSQL
  • Visual querying


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