Method of estimating an amount of changed data over plurality of intervals of time measurements

• US 6,535,870 B1
• Filed: 02/09/2000
• Issued: 03/18/2003
• Est. Priority Date: 02/09/2000
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Friske, Craig Alan, Ruddy, James Alan, Garth, John Marland
• Primary Examiner(s): CHANNAVAJJALA, SRIRAMA T
• Application Number:
  US09/501,486
• Time in Patent Office: 1,133 Days
• Field of Search: 707/1-7, 707/9-10, 707/100-104, 707/200-205, 709/220-224, 709/247-248, 709/123, 709/108, 709/181-182, 700/109
• US Class Current: 1/1
• CPC Class Codes: G06F 16/2358 Change logging, detection, and notification replication G06F16/27
• CPC Class Codes: Y10S 707/99932 Access augmentation or optimizing
• CPC Class Codes: Y10S 707/99933 Query processing, i.e. searching
• CPC Class Codes: Y10S 707/99936 Pattern matching access

Abstract

A technique for identifying changes in a data store connected to a computer. Initially, one or more interval changes are measured. Each interval change indicates an amount of change in the data store at an interval. Next, a data store change is estimated that indicates an amount of change in the data store across all of the intervals using each interval change.

Claims

1. A method of estimating an amount of changed data stored within a data store based on changes made over a plurality of intervals of time, the data store having a plurality of data elements stored therein, the method comprising:

measuring, for each of the plurality of intervals of time, a number of data elements that change in the interval;

estimating a number of data elements that changed during more than one of the intervals; and

estimating across the plurality of intervals a total number of data elements that changed using the measured number of changed data elements and taking into consideration the estimated number of data elements that changed during more than one of the intervals.

2. The method of claim 1, wherein the total number of data elements that changed is estimated by summing a percentage of elements changed during each of the intervals, and subtracting from said sum a product of the percentage of elements changed during each of the intervals.

3. The method of claim 2, wherein said elements are records in a database within the data store.

4. The method of claim 2, wherein said elements are pages in a database within the data store.

5. The method of claim 1, wherein the total number of data elements that changed is estimated by (((P₀+P_1′

−

P₀*P_1′

)*N₀)+D₁)/N₁ where P₀ is a percent of changed elements at an interval T₀, P_1′

=C_1′

/N₁, where C_1′

=C₁−

D₁, C₁=N₁*P₁, N₀ is a total number of elements at interval T₀, N₁ is a total number of elements at an interval T₁, P₁ is a percent of changed elements at interval T₁, and D₁=N₁−

N₀.

6. The method of claim 1, wherein the data store change is estimated by summing a number of changed elements at a first interval, a number of changed elements at a second interval, and a number of elements changed at both the first and second intervals, and dividing the sum by a total number of elements in the data store.

7. The method of claim 1, further comprising determining, based on the estimated total number of data elements that changed, whether to invoke an application program for performing a maintenance operation on the data store.

8. An apparatus for estimating an amount of changed data stored in a data store based on changes made over a plurality of intervals of time, comprising:

a computer having a data store coupled thereto, wherein the data store is configured for storing a plurality of data elements therein; and

a program storage unit having stored therein one or more computer programs for execution by the computer, suitable for measuring, for each of the plurality of intervals of time, data elements in the data store that changed in the interval, for estimating data elements in the data store that changed during more than one of the intervals, and for estimating across the plurality of intervals a total number of data elements that change using the measured number of changed data elements and taking into consideration the estimated number of data elements that changed during more than one of the intervals.

9. The apparatus of claim 8, wherein the total number of data elements that changed is estimated by summing a percentage of elements changed during each of the intervals, and subtracting from said sum a product of the percentage of elements changed during each of the intervals.

10. The apparatus of claim 9, wherein said elements are records in a database within the data store.

11. The apparatus of claim 9, wherein said elements are pages in a database within the data store.

12. The apparatus of claim 8, wherein the total number of data elements that changed is estimated by (((P₀+P_1′

−

P₀*P_1′

)*N₀)+D₁)/N₁ where P₀ is a percent of changed elements at an interval T₀, P_1′

=C_1′

/N₁, where C_1′

=C₁−

D₁, C₁=N₁*P₁, N₀ is a total number of elements at interval T₀, N₁ is a total number of elements at an interval T₁, P₁ is a percent of changed elements at interval T₁, and D₁=N₁−

N₀.

13. The apparatus of claim 8, wherein the total number of data elements that changed is estimated by summing a number of changed elements at a first interval, a number of changed elements at a second interval, and a number of elements changed at both the first and second intervals, and dividing the sum by a total number of elements in the data store.

14. The apparatus of claim 8, wherein said one or more computer programs are suitable for determining, based on the estimated total number of data elements that changed, whether to invoke an application program for performing a maintenance operation on the data store.

15. An article of manufacture comprising a program storage medium readable by a computer and embodying one or instructions executable by the computer to perform the method of estimating an amount of changed data stored within a data store based on changes made over a plurality of intervals of time, the data store having a plurality of data elements stored therein, the program storage medium comprising:

program instructions for measuring, for each of the plurality of intervals of time, a number of data elements that change in the interval;

program instructions for estimating a number of data elements that changed during more than one of the intervals; and

program instructions for estimating across the plurality of intervals a total number of data elements that changed using the measured number of changed data elements and taking into consideration the estimated number of data elements that changed during more than one of the intervals.

16. The article of manufacture of claim 15, wherein the total number of data elements that changed is estimated by summing a percentage of elements changed during each of the intervals, and subtracting from said sum a product of the percentage of elements changed during each of the intervals.

17. The article of manufacture of claim 16, wherein said elements are records in a database within the data store.

18. The article of manufacture of claim 16, wherein said elements are pages in a database within the data store.

19. The article of manufacture of claim 15, wherein the total number of data elements that changed is estimated by (((P₀+P_1′

−

P₀*P_1′

)*N₀)+D₁)/N₁ where P₀ is a percent of changed elements at an interval T₀, P_1′

=C_1′

/N₁, where C_1′

=C₁−

D₁, C₁−

N₁*P₁, N₀ is a total number of elements at interval T₀, N₁ is a total number of elements at an interval T₁, P₁ is a percent of changed elements at interval T₁, and D₁=N₁=N₀.

20. The article of manufacture of claim 15, wherein the total number of data elements that changed is estimated by summing a number of changed elements at a first interval, a number of changed elements at a second interval, and a number of elements changed at both the first and second intervals, and dividing the sum by a total number of elements in the data store.

21. The article of manufacture of claim 15, further comprising program instructions for determining, based on the estimated total number of data elements that changed, whether to invoke an application program for performing a maintenance operation on the data store.