System and method for recovery units in databases

• US 20050193035A1
• Filed: 02/27/2004
• Published: 09/01/2005
• Est. Priority Date: 02/27/2004
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Byrne, Peter
• Granted Patent: US 7,334,002 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1469 Backup restoration techniques
• CPC Class Codes: G06F 11/1471 involving logging of persistent data for recovery
• CPC Class Codes: G06F 2201/80 Database-specific techniques
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

The creation of multiple recoverable units within a database allows a database partition to be reconstructed during maintenance and disaster recovery operations. A method of creating a recovery unit includes partitioning a database into at least two recovery units. A primary catalog of metadata relating to the logical elements of a database such as tables, indexes, and file groups is created. A secondary catalog of metadata relating to the physical elements of a database such as pages, files, B-Trees, and log streams is created for each recovery unit. The primary and secondary metadata catalogs are linked such that only one log stream is associated with any one recovery unit. A single recovery unit may then be exercised to perform recovery or maintenance operations while the remaining recovery units of the database remain online.

Claims

1. A method of generating recoverable units in a database, the method comprising:

partitioning the database into a first and a second unit;

creating a primary catalog comprising metadata of logical elements of the units, the primary catalog referencing the units;

creating multiple logs such that any one unit is associated with only one log;

creating two secondary catalogs, each secondary catalog corresponding to a respective unit and comprising metadata of physical elements for the respective unit;

linking the primary catalog to the secondary catalogs; and

maintaining the secondary catalogs such that the first unit is recoverable independently from the second unit.

2. The method of claim 1, wherein creating two secondary catalogs further comprises creating two secondary catalogs wherein each catalog includes a log stream corresponding to the respective unit.

3. The method of claim 1, wherein linking further comprises linking the primary catalog to the secondary catalog such that a first unit is recoverable independently from the second unit while the second unit is being accessed.

4. The method of claim 1, wherein creating a primary catalog comprises creating a catalog which contains metadata for at least one of the database, tables, indexes, data types, constraints, stored procedures, triggers, and file groups.

5. The method of claim 1, wherein creating two secondary catalogs comprises creating catalogs which contain metadata for at least one of pages, files, B-Trees, heaps, and log data.

6. The method of claim 1, wherein maintaining comprises separately logging updates to the respective units in the respective secondary catalogs.

7. A system having a database, the system comprising:

a processor having access to memory, the memory having instructions which, when executed, perform the method comprising;

partitioning the database into a first and a second unit;

creating a primary catalog comprising metadata of logical elements of the units, the primary catalog referencing the units;

creating multiple logs such that any one unit is associated with only one log;

creating two secondary catalogs, each secondary catalog corresponding to a respective unit and comprising metadata of physical elements for the respective unit;

linking the primary catalog to the secondary catalogs; and

maintaining the secondary catalogs such that the first unit is recoverable independently from the second unit.

8. The system of claim 7, wherein the method step of creating two secondary catalogs further comprises creating two secondary catalogs wherein each catalog includes a log stream corresponding to the respective unit.

9. The system of claim 7, wherein the method step of linking further comprising linking the primary catalog to the secondary catalog such that a first unit is recoverable independently from the second unit while the second unit is being accessed.

10. The system of claim 7, wherein the method step of maintaining comprises separately logging updates to the respective units in the respective secondary catalogs.

11. The system of claim 7, wherein the method step of maintaining comprises separately logging updates to the respective units in the respective secondary catalogs.

12. A computer-readable medium having computer-executable instructions for performing a method, the method comprising:

partitioning the database into a first and a second unit;

creating a primary catalog comprising metadata of logical elements of the units, the primary catalog referencing the units;

creating multiple logs such that any one unit is associated with only one log;

creating two secondary catalogs, each secondary catalog corresponding to a respective unit and comprising metadata of physical elements for the respective unit;

linking the primary catalog to the secondary catalogs; and

maintaining the secondary catalogs such that the first unit is recoverable independently from the second unit.

13. The computer-readable medium of claim 12, wherein the step of creating two secondary catalogs further comprises creating two secondary catalogs wherein each catalog includes a log stream corresponding to the respective unit.

14. The computer-readable medium of claim 12, wherein the step of linking further comprises linking the primary catalog to the secondary catalog such that a first unit is recoverable independently from the second unit while the second unit is being accessed.

15. The computer-readable medium of claim 12, wherein the step of creating a primary catalog comprises creating a catalog which contains metadata for at least one of the database, tables, indexes, data types, constraints, stored procedures, triggers, and file groups.

16. The computer-readable medium of claim 12, wherein the step of creating two secondary catalogs comprises creating catalogs which contain metadata for at least one of pages, files, B-Trees, heaps, and log data.

17. The computer-readable medium of claim 12, wherein the step of maintaining comprises separately logging updates to the respective units in the respective secondary catalogs.