NoSQL databases are preferred to relational ones for stor- ing heterogeneous data with variable schema and structure. However, their schemaless nature adds complexity to analytical applications, in which a single OLAP analysis often involves large sets of data with different schemas. In this tutorial we describe the main approaches to enable OLAP on NoSQL data. We start from schema-on-read approaches, where data are left unchanged in their structure until they are accessed by the user, so they are put into multidimensional form at query time. Specifically, we show how this enables a form of approximated OLAP that embraces the inherent variety of schemaless data. Then we move to schema-on-write approaches, where a fixed multidimensional structure is forced onto data, which are loaded into a data warehouse to be then queried. In particular, we introduce multi-model data warehouses as a way to store data in multidimensional form and, at the same time, let each piece of data be natively represented through the most appropriate NoSQL model.

OLAP and NoSQL: Happily Ever After / Stefano Rizzi. - ELETTRONICO. - 13389:(2022), pp. 35-44. (Intervento presentato al convegno 26th East-European Conference on Advances in Databases and Information Systems tenutosi a Turin, Italy nel Sept. 5-8, 2022) [10.1007/978-3-031-15740-0_4].

OLAP and NoSQL: Happily Ever After

Stefano Rizzi
2022

Abstract

NoSQL databases are preferred to relational ones for stor- ing heterogeneous data with variable schema and structure. However, their schemaless nature adds complexity to analytical applications, in which a single OLAP analysis often involves large sets of data with different schemas. In this tutorial we describe the main approaches to enable OLAP on NoSQL data. We start from schema-on-read approaches, where data are left unchanged in their structure until they are accessed by the user, so they are put into multidimensional form at query time. Specifically, we show how this enables a form of approximated OLAP that embraces the inherent variety of schemaless data. Then we move to schema-on-write approaches, where a fixed multidimensional structure is forced onto data, which are loaded into a data warehouse to be then queried. In particular, we introduce multi-model data warehouses as a way to store data in multidimensional form and, at the same time, let each piece of data be natively represented through the most appropriate NoSQL model.
2022
Advances in Databases and Information Systems. ADBIS 2022
35
44
OLAP and NoSQL: Happily Ever After / Stefano Rizzi. - ELETTRONICO. - 13389:(2022), pp. 35-44. (Intervento presentato al convegno 26th East-European Conference on Advances in Databases and Information Systems tenutosi a Turin, Italy nel Sept. 5-8, 2022) [10.1007/978-3-031-15740-0_4].
Stefano Rizzi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/892067
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