Database repository with deferred transactions

• US 6,480,847 B1
• Filed: 01/29/1999
• Issued: 11/12/2002
• Est. Priority Date: 10/18/1996
• Status: Expired due to Term

• Current Assignee: Group 1 Software Inc. (Böwe Systec AG)
• Original Assignee: Sagent Technology, Inc. (Böwe Systec AG)
• Inventors: Powers, Craig R., Gorelik, Vladimir, Powers, Robert E., Netsch, Tana C., Linenbach, Terris J.
• Primary Examiner(s): Robinson, Greta
• Assistant Examiner(s): Black, Linh
• Application Number:
  US09/240,733
• Time in Patent Office: 1,383 Days
• Field of Search: 707/1-10, 707/100-104, 707/200-205, 711/168, 711/1-6, 711/100-106, 711/147-165, 700/1-4, 700/19-20, 700/53, 703/1, 709/100-108, 709/1
• US Class Current: 707/600
• CPC Class Codes: G06F 16/2343 Locking methods, e.g. distributed locking or locking implementation details
• CPC Class Codes: G06F 16/2379 Updates performed during online database operations; commit processing
• CPC Class Codes: G06F 16/252 between a Database Management System and a front-end application
• CPC Class Codes: Y10S 707/954 Relational
• CPC Class Codes: Y10S 707/99938 Concurrency, e.g. lock management in shared database
• CPC Class Codes: Y10S 707/99945 Object-oriented database structure processing
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

A deferred transaction mechanism facilitates multi-threaded operation of database application programs. The deferred transaction mechanism allows data items to be committed from the local memory of a computer system to a database system in a background thread, while other foreground threads continue to read the data item. In most instances, this makes the delay in committing a data item to the database imperceptible to a human user of a database application program. The deferred transaction mechanism further supports an “undo” feature, which allows modifications to a data item located in a computer'"'"'s local memory to be rapidly discarded.

Claims

1. An apparatus for modifying a data item, comprising:

a client computer system including a first memory to store said data item, wherein said data item is modified in response to a request of a user of the client computer system;

a database server, coupled to said client computer system, to store a plurality of data items including said data item;

said computer system including a plurality of processes comprising at least one user process and at least one other process;

wherein the client computer system is operable to create a lock on the data item being modified to allow said at least one user process to read the modified data item from said first memory, while said at least one other process writes the modified data item from said first memory to said database server.

2. The apparatus of claim 1, wherein said client computer system includes a user interface for modifying said data item in response to user input.

3. The apparatus of claim 1, wherein said client computer system is to create a write lock on said data item, the write lock blocking said at least one other process from reading said data item and writing to said data item.

4. The apparatus of claim 1, in which said lock is a read lock blocking said plurality of processes from writing to said data item.

5. The apparatus of claim 1, wherein said at least one other process includes an event process to release said read lock.

6. The apparatus of claim 1, wherein said database server comprises a database management system.

7. The apparatus of claim 6 further comprising at least one on-line transaction processing system to access said database management system.

8. The apparatus of claim 6 further comprising a data warehouse to access said database management system.

9. A method for selectively undoing modification to a data item, comprising:

creating in a first memory an original version of a data item that is stored in a database server, the first memory being included in a client computer system coupled to the database server;

making a first copy of the original version in the first memory;

modifying said first copy of the original version in the first memory;

creating a second copy from said original version in the first memory, when a command is received to undo said modifications; and

creating a new data item in the database server from the modified first copy of the original version, when a command is received to commit said modifications.

10. The method of claim 9, wherein the database server comprises a database management system.

11. The method of claim 9 further comprising storing the modified first copy of the original version to a relational database.

12. The method of claim 10, wherein said data item comprises metadata, which describes relationships between data items in said database management system.

13. The method of claim 9, wherein creating a new data item from said copy comprises:

setting a read lock on said modified first copy in the first memory, which allows said plurality of processes to read said modified first copy, but blocks said plurality of processes from modifying said modified first copy;

creating a new data item from said modified first copy;

copying said modified first copy from said first memory to said database server, wherein a time interval to create said new data item and to copy said modified first copy defines a copy latency;

reading said modified first copy during said copy latency; and

releasing said read lock.

14. An apparatus for selectively undoing modification to a data item, comprising:

a database server to store a plurality of data items, including a particular data item; and

a client computer system, coupled to the database server, to create a first copy of the particular data item in a first memory of the client computer system, to modify the first copy of the particular data item in the first memory, to create a second copy of the particular data item in the first memory when receiving a command to undo the modification, and to trigger a creation of a new data item in the database server from the modified first copy of the particular data item when receiving a command to commit the modification.

15. A machine-readable medium containing instructions which, when executed by a processing system, cause the processing system to:

create in a first memory an original version of a data item that is stored in a database server, the first memory being included in a client computer system coupled to the database server;

make a first copy of the original version in the first memory;

modify said first copy of the original version in the first memory;

create a second copy from said original version in the first memory, when a command is received to undo said modifications; and

create a new data item in the database server from the modified first copy of the original version, when a command is received to commit said modifications.