nD-SQL: A Multi-Dimensional Language for Interoperability and OLAP
Frédéric Gingras, Laks V. S. Lakshmanan · 1998
We propose a multi-dimensional language called nD-SQL with the following features: (i) nD-SQL supports queries that interoperate amongst multiple relational sources with heterogeneous schemas, including RDBMS and relational data marts, overcoming the mismatch between data and schema; (ii) it supports complex forms of restructuring that permit the visualization of n- dimensional data using the three physical dimensions of the relational model, viz., row, column, and relation; (iii) it captures sophisticated aggregations involving multiple granularities, to an arbitrary degree of resolution compared to CUBE, ROLLUP, and DRILLDOWN. We propose a formal model for a federation of relational sources and illustrate nD-SQL against it. We propose an extension to relational algebra, called restructuring relational algebra (RRA), capable of restructuring and aggregation. We propose an architecture for the implementation of an nD-SQL server, based on translating nD-SQL queries into equivalent RR...