Systems and methods for a large object infrastructure in a database system

• US 20050187893A1
• Filed: 02/10/2004
• Published: 08/25/2005
• Est. Priority Date: 02/10/2004
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Stefani, Stefano, Ashwin, Shrinivas, Surna, Aleksandras, Kleinerman, Christian, Fang, Jun, Kalhan, Ajay, Blakeley, Jose A., Zhang, Honggang, Carlin, Peter
• Granted Patent: US 7,437,346 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/24562 Pointer or reference processing operations
• CPC Class Codes: Y10S 707/99931 Database or file accessing
• CPC Class Codes: Y10S 707/99936 Pattern matching access
• CPC Class Codes: Y10S 707/99943 Generating database or data structure, e.g. via user interface

Abstract

Various embodiments of the present invention are direct to the utilization of Blob Handles (BHs) which are an internal representation of a large value. BHs are immutable and stateless references to a large data object. The structure of a BH contains enough information to return an ILockBytes interface in order to provide access to the corresponding large data block, and a BH can also return information regarding its own lifetime description. A BH can be completely described using (a) a pointer to the beginning of BH data and (b) the byte-length of the BH.

Claims

1. A method for handling a large data object in a computer system, said method comprising creating a handling structure representing the large data object, wherein said handling structure can be processed by said computer system, via functions, operations, and so forth available for a small data object, with which said large data object could not be so processed.

2. The method of claim 1 wherein a first handling structure pointing to a first large data object is virtually copied by the creation of a second handling structure that points to the same first large data object provided that the first handling structure and the second handling structure do not write a change to said first large data object.

3. The method of claim 2 wherein, if said first handling structure must write a change to said first large data object, said first large data object is copied to a second large data object and said second handling structure is pointed to said second large data object prior to the first handling structure writing the change to the first large data object.

4. The method of claim 2 wherein, if said second handling structure must write a change to said first large data object, said first large data object is copied to a second large data object and said second handling structure is pointed to said second large data object, and then said second handling structure will write the change to the second large data object.

5. The method of claim 1 wherein a data object having a type from among the group of types comprising text, ntext, and image data types (or their equivalents) is converted into a large data object with a corresponding handling structure.

6. The method of claim 5 wherein a data object of type text, ntext, or image data type (or an equivalent data type) is converted into a data object of type varchar(MAX), nvarchar(MAX), or varbinary(MAX) (or an equivalent data type) respectively wherein varchar(MAX), nvarchar(MAX), and varbinary(MAX) comprise a handling structure and the MAX corresponds to a predetermined maximum size value.

7. The method of claim 1 wherein said handling structure corresponds to a small value data object, and said small value data object is stored entirely within the said handling structure.

8. The method of claim 1 further comprising a delete operation for said handling structure, wherein if said handling structure is of a first type, said handling structure and a corresponding large data object are both deleted, and wherein if said handling structure is of a second type, only said handling structure, and not said corresponding large data object, is deleted.

9. The method of claim 1 wherein said handling structure has a lifetime, and said handling structure comprising a field having a value corresponding to said lifetime.

10. The method of claim 1 wherein said handling structure is created by a handling structure factory in response to a need for a handling structure.

22. The computer-readable instructions of claim 1 further comprising instructions whereby a first handling structure pointing to a first large data object is virtually copied by the creation of a second handling structure that points to the same first large data object provided that the first handling structure and the second handling structure do not write a change to said first large data object.

23. The computer-readable instructions of claim 2 further comprising instructions whereby, if said first handling structure must write a change to said first large data object, said first large data object is copied to a second large data object and said second handling structure is pointed to said second large data object prior to the first handling structure writing the change to the first large data object.

24. The computer-readable instructions of claim 2 further comprising instructions whereby, if said second handling structure must write a change to said first large data object, said first large data object is copied to a second large data object and said second handling structure is pointed to said second large data object, and then said second handling structure will write the change to the second large data object.

25. The computer-readable instructions of claim 1 further comprising instructions whereby a data object having a type from among the group of types comprising text, ntext, and image data types (or their equivalents) is converted into a large data object with a corresponding handling structure.

26. The computer-readable instructions of claim 5 further comprising instructions whereby a data object of type text, ntext, or image data type (or an equivalent data type) is converted into a data object of type varchar(MAX), nvarchar(MAX), or varbinary(MAX) (or an equivalent data type) respectively, said varchar(MAX), nvarchar(MAX), and varbinary(MAX) types comprising a handling structure type, and a MAX value corresponds to a predetermined maximum size value.

27. The computer-readable instructions of claim 1 further comprising instructions whereby, if said handling structure corresponds to a small value data object, said small value data object is stored entirely within the said handling structure.

28. The computer-readable instructions of claim 1 further comprising instructions for a delete operation for said handling structure, said delete operation comprising instructions whereby if said handling structure is of a first type, said handling structure and a corresponding large data object are both deleted, and further comprising instructions whereby if said handling structure is of a second type, only said handling structure, and not said corresponding large data object, is deleted.

29. The computer-readable instructions of claim 1 further comprising instructions whereby said handling structure has a lifetime, and said handling structure comprising a field having a value corresponding to said lifetime.

30. The computer-readable instructions of claim 1 further comprising instructions whereby said handling structure is created by a handling structure factory in response to a need for a handling structure.

11. A system for handling a large data object in a computer system, said method comprising a subsystem for creating a handling structure representing the large data object, wherein said handling structure can be processed by said computer system, via functions, operations, and so forth available for a small data object, with which said large data object could not be so processed.

12. The system of claim 11 wherein a first handling structure pointing to a first large data object is virtually copied by the creation of a second handling structure that points to the same first large data object provided that the first handling structure and the second handling structure do not write a change to said first large data object.

13. The system of claim 12 wherein, if said first handling structure must write a change to said first large data object, said first large data object is copied to a second large data object and said second handling structure is pointed to said second large data object prior to the first handling structure writing the change to the first large data object.

14. The system of claim 12 wherein, if said second handling structure must write a change to said first large data object, said first large data object is copied to a second large data object and said second handling structure is pointed to said second large data object, and then said second handling structure will write the change to the second large data object.

15. The system of claim 11 wherein a data object having a type from among the group of types comprising text, ntext, and image data types (or their equivalents) is converted into a large data object with a corresponding handling structure.

16. The system of claim 15 wherein a data object of type text, ntext, or image data type (or an equivalent data type) is converted into a data object of type varchar(MAX), nvarchar(MAX), or varbinary(MAX) (or an equivalent data type) respectively wherein varchar(MAX), nvarchar(MAX), and varbinary(MAX) comprise a handling structure and the MAX corresponds to a predetermined maximum size value.

17. The system of claim 11 wherein said handling structure corresponds to a small value data object, and said small value data object is stored entirely within the said handling structure.

18. The system of claim 11 further comprising a delete operation for said handling structure, wherein if said handling structure is of a first type, said handling structure and a corresponding large data object are both deleted, and wherein if said handling structure is of a second type, only said handling structure, and not said corresponding large data object, is deleted.

19. The system of claim 11 wherein said handling structure has a lifetime, and said handling structure comprising a field having a value corresponding to said lifetime.

20. The system of claim 11 wherein said handling structure is created by a handling structure factory in response to a need for a handling structure.

21. A computer-readable medium comprising computer-readable instructions for handling a large data object in a computer system, said computer-readable instructions comprising instructions for creating a handling structure representing the large data object, and processing said handling structure with functions, operations, and such other manipulations available for a small data object, with which said large data object could not be so processed.