From Nested-Loop to Join Queries in OODB

Most declarative SQL-like query languagesfor object-oriented database systems (OOSQL) are orthogonal languages allowing for arbitrary nesting of expressions in the select-, from-, and where-clause. Expressions in the from-clause may be basetables aswell assetvalued attributes. In this paper, we propose a general strategy for the optimization of nested OOSQL queries. As in the relational model, the translation/optimization goal is to move from tuple- to set-oriented query processing. Therefore, OOSQL is translated into the algebraic language ADL, and by meansof algebraic rewriting nested queries are transformed into join queries asfar aspossible. Three optimization options are described, and a strategy to assign priorities to options is proposed.

• Type: Conference
• Year: 1994
• Where: VLDB
• Authors: Hennie J. Steenhagen, Peter M. G. Apers, Henk M. Blanken, Rolf A. de By
• Keywords: Database, Declarative Sql-like Query, Nested Oosql Queries, Nested Queries, VLDB 1994