Method and system for implementing persistent object services on a relational database

• US 6,711,582 B2
• Filed: 06/25/2002
• Issued: 03/23/2004
• Est. Priority Date: 08/05/1999
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Rulong, Gordon Scott, Xu, Tingting, Murthy, Suresh Narayana, Aldridge, Amy S.
• Primary Examiner(s): Homere, Jean R.
• Assistant Examiner(s): Ali, Mohammad
• Application Number:
  US10/180,642
• Publication Number:
  US 20020194155A1
• Time in Patent Office: 637 Days
• Field of Search: 707/3-4, 707/102-104, 709/102, 709/209, 709/217, 709/250, 717/6.5
• US Class Current: 707/718
• CPC Class Codes: G06F 16/284 Relational databases
• CPC Class Codes: G06F 16/289 Object oriented databases
• CPC Class Codes: Y10S 707/954 Relational
• CPC Class Codes: Y10S 707/99933 Query processing, i.e. searching
• CPC Class Codes: Y10S 707/99942 Manipulating data structure, e.g. compression, compaction, compilation
• CPC Class Codes: Y10S 707/99943 Generating database or data structure, e.g. via user interface
• CPC Class Codes: Y10S 707/99944 Object-oriented database structure
• CPC Class Codes: Y10S 707/99945 Object-oriented database structure processing

Abstract

A persistent object service (POS) that interfaces to a set of one or more relational database management systems. A persistent object is mapped to one or more tables in a relational database based on the object'"'"'s attribute types and the object'"'"'s relationships with other objects. If the object inherits from another object, the mapping creates multiple tables, a top level table for base attributes, and a set of one or more child tables that contain extended attributes of the inherited objects. A routine for storing an object converts persistent object operations to a sequence of SQL statements for storing the object in the relational database.

Claims

1. A method of storing object information in a relational database, comprising the steps of:

extracting object information relating to an object from a stream;

constructing an initial SQL statement from the extracted object information;

responsive to a failure of the initial SQL statement, constructing a second SQL statement from the extracted object information, wherein the initial SQL statement is an insert statement and the second SQL statement is an update statement, or wherein the initial SQL statement is an update statement and the second SQL statement is an insert statement; and

storing the object information.

2. The method as described in claim 1 wherein an insert statement fails if information for the object is already present in the relational database.

3. The method as described in claim 1 wherein the object information is stored according to the initial statement.

4. The method as described in claim 1 wherein the object information is stored according to the second statement.

5. The method as described in claim 1 wherein the object information is mapped to one or more tables in the relational database according to attributes in the object and their respective relationships with other objects.

6. The method as described in claim 5 wherein a base table in the relational database has a set of base attributes and a set of one or more child tables related to the base table.

7. The method as described in claim 6 wherein a given child table includes only extended attributes of inherited objects.

8. The method as described in claim 1 wherein the relational database is one of a set of relational databases.

9. An apparatus for storing object information in a relational database, the apparatus comprising:

means for extracting object information relating to an object;

means for constructing an initial SQL statement from the extracted object information;

means responsive to a failure of the initial SQL statement for constructing a second SQL statement from the extracted object information, wherein the initial SQL statement is an insert statement and the second SQL statement is an update statement, or wherein the initial SQL statement is an update statement and the second SQL statement is an insert statement; and

means for storing the object information.

10. The apparatus as described in claim 9 further including means for mapping object information to one or more tables in the relational database according to attributes in the object and their respective relationships with other objects.

11. The apparatus as described in claim 9 wherein the mapping means generates a base table in the relational database having a set of base attributes and a set of one or more child tables related to the base table.

12. The apparatus as described in claim 11 wherein a given child table includes only extended attributes of inherited objects.

13. A computer program product in a computer readable medium for use in a data processing system for storing object information in a relational database, the computer program product comprising:

means for extracting object information relating to an object;

means for constructing an initial SQL statement from the extracted object information;

means responsive to a failure of the initial SQL statement for constructing a second SQL statement from the extracted object information, wherein the initial SQL statement is an insert statement and the second SQL statement is an update statement, or wherein the initial SQL statement is an update statement and the second SQL statement is an insert statement; and

means for storing the object information.

14. The computer program product as described in claim 13 further including means for mapping object information to one or more tables in the relational database according to attributes in the object and their respective relationships with other objects.

15. The computer program product as described in claim 13 wherein the mapping means generates a base table in the relational database having a set of base attributes and a set of one or more child tables related to the base table.

16. The computer program product as described in claim 15 wherein a given child table includes only extended attributes of inherited objects.