Patent ID: 8005807
Filing Date: 2011-08-23
Classification: G06F,Y10S

Abstract:
1. An article of manufacture for use in a computer system for translating a path expression in an object oriented query to a relational database outer join, said path expression comprising a navigation path through a relationship in a schema, said article of manufacture comprising a computer-useable storage medium having a computer program embodied in said medium which causes the computer system to perform: analyzing each path expression defined in each level of the object oriented query; identifying each path expression which can be a candidate for a translation to an outer join; ordering the path expression starting with path expression defined in a FROM clause, adding to the FROM clause path expression, each path expression identified as a candidate for a translation to an outer join, and making the ordered path expressions as input to a select operator for each level of the object oriented query; grouping the ordered path expressions sequentially based upon on a source-target dependency between ordered path expressions and based upon the identifications as a candidate for a translation to an outer join; creating a quantifier for each path expression, said quantifier comprising a variable representing a table in a relational database; replacing each grouped path expression with a corresponding quantifier and related table in a relational database; performing optimization on grouped quantifiers, said optimization identifying quantifiers which can be a candidate for a translation to an inner join; generating an outer join for each quantifier which remains after optimization a candidate for a translation to an outer join; generating an inner join for each quantifier which remains after optimization a candidate for a translation to an inner join; and completing a translation of the object oriented query to a relational query.