Method of checking the validity of a set of digital information, and a method and an apparatus for retrieving digital information from an information source

• US 6,564,218 B1
• Filed: 11/12/1999
• Issued: 05/13/2003
• Est. Priority Date: 12/10/1998
• Status: Expired due to Fees

• Current Assignee: PremiTech A/S (Capasystems A/S)
• Original Assignee: Premitech APS
• Inventors: Roth, Martin Josef
• Primary Examiner(s): Robinson, Greta
• Assistant Examiner(s): Black, Linh
• Application Number:
  US09/439,806
• Time in Patent Office: 1,278 Days
• Field of Search: 707/1-10, 707/100-104, 707/200-206, 707/500-542, 714/400, 714/1-57, 714/699-824, 709/248
• US Class Current: 1/1
• CPC Class Codes: G06F 16/9574 of access to content, e.g. by caching
• CPC Class Codes: Y10S 707/99931 Database or file accessing
• CPC Class Codes: Y10S 707/99932 Access augmentation or optimizing
• CPC Class Codes: Y10S 707/99939 Privileged access
• CPC Class Codes: Y10S 707/99945 Object-oriented database structure processing

Abstract

The invention disclosed herein is a method of checking the validity of a set of digital information contained in an information cache connected to an information source. The method includes specifying two or more overlapping supersets of information having the set of digital information as a common subset; and performing the validity check of the set of digital information by comparing validity information associated with one or more of the supersets in the cache and validity information associated with corresponding supersets in the information source. Disclosed herein is a method of and apparatus for retrieving digital information from an information source having a cache connected thereto.

Claims

1. A method of checking the validity of a set of digital information contained in cache means connected to an information source by comparing validity information associated with said set of digital information and validity information associated with corresponding digital information in said information source, characterized by

specifying two or more overlapping supersets of information having said set of digital information as a common subset;

and

performing said validity check by comparing validity information associated with one or more of said supersets in said cache means and validity information associated with corresponding supersets in said information source.

2. A method according to claim 1, characterized in that said set of digital information is identified as valid when at least one of said supersets is valid.

3. A method according to claim 2, characterized in that said one or more supersets to be used for said validity check are selected from said specified supersets on the basis of a priori knowledge of supersets least likely to be updated.

4. A method according to claim 2, characterized in that said one or more supersets to be used for said validity check are selected from said specified supersets on the basis of obtained knowledge of supersets having been updated least frequently.

5. A method of retrieving digital information from an information source having cache means connected thereto, said method comprising the steps of;

receiving a query specifying the digital information to be retrieved;

checking whether said cache means holds query result information associated with said query, and in the affirmative performing a validity check of said query result information;

retrieving, if said cache means does not hold valid query result information associated with said query, valid query result information from said information source and updating said cache Leans with said retried valid query result information; and

presenting said valid query result information as a result of said query,

characterized in that said checking includes specifying two or more overlapping supersets of information having query result information associated with said query as a common subset; and

said validity check is performed by comparing validity information associated with one or more of said supersets in said cache means and validity information associated with corresponding supersets in said information source.

6. A method according to claim 5, characterized in that query result information in a common subset is identified as valid when at least one of said supersets is valid.

7. A method according to claim 6, characterized in that said one or more supersets to be used for said validity check are selected among said specified supersets on the basis of a priori knowledge of supersets least likely to be updated.

8. A method according to claim 6, characterized in that said one or more supersets to be used for said validity check are selected from said specified supersets on the basis of obtained knowledge of supersets having been updated least frequently.

9. An apparatus for retrieving digital information from an information source having cache means connected thereto, said apparatus comprising:

input means adapted to receive a query specifying the digital information to be retrieved;

checking means adapted to check if said cache means holds query result information associated with said query, and in the affirmative performing a validity check of said query result information;

updating means adapted, whether said cache means does not hold valid query result information associated with said query, to retrieve valid query result information from said information source and to update said cache means with said retrieved valid query result information; and

output means adapted to present said valid query result information as a result of said query

characterized in that said checking means is adapted to specify two or more overlapping supersets of information having query result information associated with said query as a common subset; and

to perform said validity check by comparing validity information associated with one or more supersets in said cache means and validity information associated with corresponding supersets in said information source.

10. An apparatus according to claim 9 characterized in that said checking means is adapted to identify query result information in a common subset as valid when at least one of said supersets is valid.

11. An apparatus according to claim 10, characterized in that said checking means is adapted to select said one or more supersets to be used for said validity check from said specified supersets on the basis of a priori knowledge of supersets least likely to be updated.

12. An apparatus according to claim 10, characterized in that said checking means is adapted to select said one or more supersets to be used for said validity check from said specified supersets on the basis of obtained knowledge of supersets having been updated least frequently.