Database Caching and Invalidation Based on Detected Database Updates

• US 20060271557A1
• Filed: 05/25/2006
• Published: 11/30/2006
• Est. Priority Date: 05/25/2005
• Status: Abandoned Application

• Current Assignee: Terracotta, Inc. (Software AG)
• Original Assignee: Terracotta, Inc. (Software AG)
• Inventors: Harward, Nathaniel D., Voskoboynik, Alexander, Geweke, Andrew R.
• Application Number:
  US11/420,460
• Publication Number:
  US 20060271557A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1479 Generic software techniques for error detection or fault masking
• CPC Class Codes: G06F 11/203 using migration
• CPC Class Codes: G06F 16/217 Database tuning G06F16/2282 takes precedence; database performance monitoring G06F11/3409
• CPC Class Codes: G06F 16/24552 Database cache management
• CPC Class Codes: G06F 2209/522 Manager
• CPC Class Codes: G06F 9/445 Program loading or initiating bootstrapping G06F9/4401; security arrangements for program loading or initiating G06F21/57
• CPC Class Codes: G06F 9/45504 Abstract machines for programme code execution, e.g. Java virtual machine [JVM], interpreters, emulators
• CPC Class Codes: G06F 9/52 Program synchronisation; Mutual exclusion, e.g. by means of semaphores
• CPC Class Codes: G06F 9/526 Mutual exclusion algorithms
• CPC Class Codes: G06F 9/544 Buffers; Shared memory; Pipes

Abstract

Database data is reliably maintained and invalidated based on actual changes to data in the database. The dependencies of a received query can be determined by submitting a version of the received query to the database through a native facility provided by the database to analyze how query structures are processed. The caching system can access the results of the facility to determine the tables, rows, or other partitions of data a received query is dependent upon or modifies. An abstracted form of the query can be cached with an indication of the tables, rows, etc. that queries of that structure access or modify. The tables a write or update query modifies can be cached with a time of last modification. A component can be implemented at or on the system of the database to directly detect changes to the database data. This component can monitor transactional information maintained by the database itself to determine when changes to the database occur. This component can communicate with the cache to provide notification of changes to the database.

Claims

1. A method of caching database query results;

maintaining at a caching system one or more queries and results received from a database in response to said one or more queries;

monitoring information maintained by said database indicating transactions executed at said database;

detecting a change to said information maintained by said database;

accessing at least a portion of said information maintained by said database to determine if portions of said database have been modified; and

providing a notification to said caching system of portions of said database that have been modified if said accessing determines that portions have been modified.

2. The method of claim 1, wherein:

said maintaining at a caching system comprises maintaining at a caching system at an application server said one or more queries and results;

said monitoring information maintained by said database comprises monitoring at a database server said information maintained by said database, said database executes at said database server, said database server is remote from said application server;

said providing a notification comprises providing said notification from said database server to said application server.

3. The method of claim 1, wherein monitoring information maintained by said database includes gaining access to a process at said database that writes said information maintained by said database.

4. The method of claim 3, wherein:

gaining access includes instructing an operating system associated with said database to provide a notification when said process issues a write request.

5. The method of claim 4, wherein:

said instructing includes instructing said operating system as a debugger for said process.

6. The method of claim 3, wherein:

gaining access includes interfacing between said operating system and a storage system to which said process writes said information as a driver for said storage system.

7. A database caching system, comprising:

a database server;

a database executing at said database server;

an application server in communication with said database server;

a listener component at said database server, said listener component accesses information maintained by said database indicating transactions affecting database data and in response to a change to said information maintained by said database, issues a notification of said change to said application server;

a caching system for said database located at said application server, said caching system maintains information including requests issued to said database and results received from said database in response to said requests, said caching system receives said notification of said change from said listener component and in response, updates said information to reflect said change to said database data.

8. The database caching system of claim 7, wherein:

said database server includes an operating system;

said database includes a transaction writer that maintains said information indicating operations affecting database data on a non-volatile storage medium;

said listener component attaches itself to said transaction writer as a debugger and instructs said operating system to notify it when said transaction writer writes said information to said non-volatile storage medium, said listener component receives at least a portion of said information from said operating system to determine said change to said data.

9. The database caching system of claim 8. wherein:

said listener component instructs said operating system to notify it when said non-volatile storage medium indicates that said information has been successfully written.

10. The database caching system of claim 9 wherein:

said listener component instructs said operating system to notify it when a write command is issued to said non-volatile storage medium to write said information to said non-volatile storage medium.

11. The database caching system of claim 8 wherein:

said listener component instructs said operating system to pause said transaction writer;

said caching system responds to said listener component when said information has been updated to reflect said change to said database data; and

said listener component receives said response and after receiving said response, instructs said operating system to free said transaction writer from said pause.

12. The database caching system of claim 7, wherein:

said database server includes an operating system;

said database includes a transaction writer that maintains said information indicating operations affecting database data on a non-volatile storage medium;

said listener component presents itself to said operating system as a file system driver for said non-volatile storage medium.

13. The database caching system of claim 12. wherein:

said transaction writer writes said information to said non-volatile storage medium by issuing a request to said operating system to write said information to said non-volatile storage medium;

said operating system issues a request to said listener component to write said information to said non-volatile storage medium;

said listener component passes said request to an actual file system driver for said non-volatile storage medium and accesses said information after receiving said request from said operating system to write said information;

14. The database caching system of claim 13, wherein:

said listener component accesses said information by reading said information from said non-volatile storage medium after receiving said request and after said information has been written to said non-volatile storage medium.

15. The database caching system of claim 13, wherein:

said listener component accesses at least a portion of said information by accessing said at least a portion of said information from said request issued by said operating system.

16. The database caching system of claim 7, wherein:

said listener component parses at least a portion of said information maintained by said database upon detecting said change to said information, said listener component parses said at least a portion of said information to determine if any tables of said database were modified;

said notification of said change issued by said listener component to said application server indicates any tables modified at said database.

17. One or more processor readable storage devices having processor readable code embodied on said one or more processor readable storage devices, said processor readable code for programming one or more processors to perform a method comprising:

maintaining at a caching system one or more queries and results received from a database in response to said one or more queries;

monitoring information maintained by said database indicating transactions executed at said database;

detecting a change to said information maintained by said database;

accessing at least a portion of said information maintained by said database to determine if portions of said database have been modified; and

providing a notification to said caching system of portions of said database that have been modified if said accessing determines that portions have been modified.