Apparatus and Method for Utilizing Context to Resolve Ambiguous Queries

• US 20100121837A1
• Filed: 11/13/2008
• Published: 05/13/2010
• Est. Priority Date: 11/13/2008
• Status: Active Grant

• Current Assignee: SAP France SA (SAP SE)
• Original Assignee: Business Objects SA (SAP SE)
• Inventors: Cras, Jean-Yves "YANNICK", Delacourt, Yann, Mariani, Pascale, Vergnory-Mion, Gilles
• Granted Patent: US 8,423,523 B2
• Time in Patent Office: Days
• US Class Current: 707/713
• CPC Class Codes: G06F 16/20 of structured data, e.g. relational data
• CPC Class Codes: G06F 16/2456 Join operations

Abstract

A computer readable storage medium includes executable instructions to derive from a database schema an irreducible ambiguous group comprising a sub-schema with a set of vertices wherein any two vertices are part of a loop. Contexts are defined on the sub-schema. For each context, joins in the sub-schema are designated as mandatory joins, excluded joins and neutral joins. A selection of a context from multiple contexts invoked by a path characterizing a query is processed. The query is resolved using the context.

Claims

1. A computer readable storage medium, comprising executable instructions to:

derive from a database schema an irreducible ambiguous group comprising a sub-schema with a set of vertices wherein any two vertices are part of a loop;

designate joins in the sub-schema as mandatory joins, excluded joins and neutral joins; and

define a context as a list of selected joins in the sub-schema.

2. The computer readable storage medium of claim 1 further comprising executable instructions to resolve a query using the context.

3. The computer readable storage medium of claim 2 further comprising executable instructions to process a selection of a context from multiple contexts invoked by a path characterizing the query.

4. The computer readable storage medium of claim 2 further comprising executable instructions to compute a tree that covers all tables invoked by the query.

5. The computer readable storage medium of claim 2 further comprising executable instructions to remove sub-schema joins that are excluded joins.

6. The computer readable storage medium of claim 2 further comprising executable instructions to remove any context with mandatory joins excluded by a selected element.

7. The computer readable storage medium of claim 1 further comprising executable instructions to form one context per fact table.

8. The computer readable storage medium of claim 1 further comprising executable instructions to build a list of irreducible ambiguous groups.

9. The computer readable storage medium of claim 8 further comprising executable instructions to populate the list utilizing collapsed table criteria.

10. The computer readable storage medium of claim 9 wherein the collapsed table criteria includes first criteria for processing one collapsed table.

11. The computer readable storage medium of claim 9 wherein the collapsed table criteria includes second criteria for processing two or more collapsed tables.

12. The computer readable storage medium of claim 9 wherein the collapsed table criteria includes third criteria for processing tables that do not include a collapsed table.

13. The computer readable storage medium of claim 12 further comprising executable instructions to form a collapsed table.

14. The computer readable storage medium of claim 1 further comprising executable instructions to form a nested context.

15. The computer readable storage medium of claim 1 wherein the sub-schema includes a contained table, a boundary table and a collapsed table.

16. A computer readable storage medium, comprising executable instructions to:

derive from a database schema a context defined by mandatory joins, excluded joins and neutral joins.

17. The computer readable storage medium of claim 16 further comprising executable instructions to create a context based upon an irreducible ambiguous group with a set of vertices wherein any two vertices are part of a loop.

18. The computer readable storage medium of claim 17 further comprising executable instructions to designate all joins outside the irreducible ambiguous group as neutral joins.

19. The computer readable storage medium of claim 16 further comprising executable instructions to form one context per fact table.

20. The computer readable storage medium of claim 16 further comprising executable instructions to receive user-selected excluded joins to form a context.

21. The computer readable storage medium of claim 16 further comprising executable instructions to utilize the context in a tree search.

22. The computer readable storage medium of claim 16 further comprising executable instructions to form a nested context.

23. The computer readable storage medium of claim 22 further comprising executable instructions to perform a tree search on the nested context.