Flashback support for domain index queries

• US 7,689,549 B2
• Filed: 10/05/2006
• Issued: 03/30/2010
• Est. Priority Date: 10/05/2006
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: Oracle International Corporation (Oracle Corporation)
• Inventors: Krishnamurthy, Sriram, Yoaz, Adiel
• Primary Examiner(s): NGUYEN, CAM LINH T
• Application Number:
  US11/544,790
• Publication Number:
  US 20070198615A1
• Time in Patent Office: 1,272 Days
• Field of Search: 707 1- 4, 707/10, 707100-102, 707/200, 707/202, 707/203
• US Class Current: 1/1
• CPC Class Codes: G06F 16/2228 Indexing structures
• CPC Class Codes: G06F 16/24524 Access plan code generation and invalidation; Reuse of access plans
• CPC Class Codes: Y10S 707/99933 Query processing, i.e. searching

Abstract

Techniques for executing flashback queries using domain indexes in a database system are provided. In one technique, a flashback parameter of the flashback query is not included in a call-out invocation of domain index routines that implement a domain index. A call-back query execution unit nonetheless retrieves, for call-back queries issued by the domain index routines, call-back query results that reflect the state of a database in the database system as of the time specified in the flashback parameter. In another technique, a call-out invocation of domain index routines includes the flashback parameter of a flashback query. The domain index routines issue call-back queries that require the retrieval of data which reflects the state of a database as of the time specified in the flashback parameter, which are executed by the call-back query execution unit.

Claims

1. A method of processing a flashback query to return data from a prior target logical state of a database system, the method comprising the steps of:

receiving, at said database system, said flashback query, wherein a response to the flashback query requires said database system to retrieve said data from said prior target logical state of said database system, where the prior target logical state corresponds to a target time; and

in response to receiving said flashback query, computing said flashback query using an index structure that is not natively supported by said database system to retrieve said data, wherein said data that is retrieved using said index structure accurately reflects said prior target logical state of said database system, but does not reflect a different logical state of said database system that exists after said target logical state;

wherein the method is performed by one or more computing devices.

2. The method of claim 1, wherein the method further includes registering with the database system user-implemented routines for using the index structure.

3. The method of claim 2, further including:

in response to receiving said flashback query, storing target time data that indicates said prior target logical state;

wherein the step of using an index structure includes making a call to at least one of said user-implemented routines without passing any information identifying said target point in time;

in response to said call, receiving from at least one of said user-implemented routines one or more second queries; and

using the target time data to execute the one or more second queries to retrieve further data that reflects said prior target logical state.

4. The method of claim 3, wherein:

the method further includes storing the stored target time data in a variable;

the step of using the target time to execute the one or more second queries is performed by a call-back execution unit; and

the call-back execution unit obtains said stored target time data from said variable.

5. The method of claim 3, wherein the step of using the target time data to execute the one or more second queries further comprises the step of rewriting said one or more second queries to retrieve said further data that reflects said prior target logical state of said database system.

6. The method of claim 2, wherein using the index structure includes:

making a call to at least one of said user-implemented routines, wherein said call passes information identifying said target time;

in response to said call, receiving from at least one of said user-implemented routines (a) one or more second queries that request retrieval of data, and (b) data that reflects said target time.

7. The method of claim 6, further comprising the step of executing the one or more second queries to retrieve further data that reflects said target logical state of said database system.

8. A computer-readable storage medium carrying one or more sequences of instructions for processing a flashback query to return data from a prior target logical state of a database system, which instructions, when executed by one or more processors, causes the one or more processors to perform:

receiving, at said database system, said flashback query, wherein a response to the flashback query requires said database system to retrieve said data from said prior target logical state of said database system, where the prior target logical state corresponds to a target time; and

in response to receiving said flashback query, computing said flashback query using an index structure that is not natively supported by said database system to retrieve said data, wherein said data that is retrieved using said index structure accurately reflects said prior target logical state of said database system, but does not reflect a different logical state of said database system that exists after said target logical state.

9. The computer-readable storage medium of claim 8, wherein the instructions further include instructions for registering with the database system user-implemented routines for using the index structure.

10. The computer-readable storage medium of claim 9, wherein the instructions further include instructions for:

in response to receiving said flashback query, storing target time data that indicates said prior target logical state;

wherein the step of using an index structure includes making a call to at least one of said user-implemented routines without passing any information identifying said target point in time;

in response to said call, receiving from at least one of said user-implemented routines one or more second queries; and

using the target time data to execute the one or more second queries to retrieve further data that reflects said prior target logical state.

11. The computer-readable storage medium of claim 10, wherein the instructions further include instructions for:

storing the stored target time data in a variable;

wherein the step of using the target time to execute the one or more second queries is performed by a call-back execution unit; and

wherein the call-back execution unit obtains said stored target time data from said variable.

12. The computer-readable storage medium of claim 10, wherein the step of using the target time data to execute the one or more second queries further comprises the step of rewriting said one or more second queries to retrieve said further data that reflects said prior target logical state of said database system.

13. The computer-readable storage medium of claim 9, wherein using the index structure includes:

making a call to at least one of said user-implemented routines, wherein said call passes information identifying said target time;

in response to said call, receiving from at least one of said user-implemented routines (a) one or more second queries that request retrieval of data, and (b) data that reflects said target time.

14. The computer-readable storage medium of claim 13, wherein the instructions further comprise carrying instructions for executing the one or more second queries to retrieve further data that reflects said target logical state of said database system.