Authors:
Lucas F. de Oliveira
;
Alessandro Elias
;
Fabiola Santore
;
Diego Pasqualin
;
Luis C. E. Bona
;
Marcos Sunyé
and
Marcos Didonet Del Fabro
Affiliation:
C3SL Labs, Informatics Department, Federal University of Paraná, Curitiba, Brazil
Keyword(s):
Analytical Querying, Open Data API, Query Generation, Relation-Free Query.
Abstract:
The large availability of tabular Open Data sources with hundreds of attributes and relations makes the query development a difficult task, where analytic queries are common. When writing such queries, often called SPJG (Select-Project-Join-GroupBy), it is necessary to understand a data model and to write JOIN operations. The most common approach is to use business intelligence frameworks, or recent solutions based on keywords or examples. However, they require the utilization of specific applications and there is a lack of support for web-based APIs. We present a solution that eases the task of query development for tabular Open Data analytics through an API, using a simplified query representation where it is not allowed to specify the data relations, and consequently neither the joins over them, called Relation-Free Query. We define a single virtual schema that captures the database structure, which allows the use of relation-free queries in existent DBMS’s. The concrete queries a
re exposed by a RESTful API, which is then translated into a database query language using known query generation solutions. The API is available as a microservice. We present a case study to describe solution, using a real world scenario to query in an integrated database of several Brazilian open databases with hundreds of attributes.
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