System and method for reliable caching of database connections in a distributed application

• US 6,434,543 B1
• Filed: 11/01/1999
• Issued: 08/13/2002
• Est. Priority Date: 11/01/1999
• Status: Expired due to Term

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Goldberg, Robert N., White, Seth J.
• Primary Examiner(s): Breene, John
• Assistant Examiner(s): LE, DEBBIE M
• Application Number:
  US09/430,874
• Time in Patent Office: 1,016 Days
• Field of Search: 707/1, 707/2-4, 707/10, 707/200
• US Class Current: 707/802
• CPC Class Codes: G06F 16/217 Database tuning G06F16/2282 takes precedence; database performance monitoring G06F11/3409
• CPC Class Codes: H04L 67/10 in which an application is distributed across nodes in the network software deployment G06F8/60; multiprogramming arrangements G06F9/46
• CPC Class Codes: H04L 67/14 Session management for real-time applications in data packet communications networks H04L65/1066
• CPC Class Codes: H04L 67/568 Storing data temporarily at an intermediate stage, e.g. caching
• CPC Class Codes: Y10S 707/955 Object-oriented
• CPC Class Codes: Y10S 707/99932 Access augmentation or optimizing
• CPC Class Codes: Y10S 707/99936 Pattern matching access
• CPC Class Codes: Y10S 707/99944 Object-oriented database structure

Abstract

Connection information for open database connections is stored or “cached” in a connection manager at the database client. Therefore, even when a query is complete and the connection between the client and server is released, the manager maintains the database connection open. When a new query arrives at the client, the connection manager compares the connection information in the query to the corresponding information stored for each open connection. If there is a match and the connection is not in use, the already open connection is used for the new query. If there is no match, a new connection is opened until a predetermined limit of the number of connections is reached. When the limit is reached, an open connection which is not in use is closed and a new connection is established. In accordance with a preferred embodiment, a “free” list of open connections which are not in use is maintained so that a quick comparison can be made with the incoming query information.

Claims

1. A system for managing connections between a server and a plurality of databases in a distributed object network in response to a server request to open a first connection and to a server request to release a second connection, the system comprising:

a connection cache for storing information representing a plurality of connections;

opening apparatus cooperating with the connection cache which responds to the server open request by opening the first connection and storing information representing the first connection in the connection cache when the connection cache does not already contain information representing the first connection; and

releasing apparatus which cooperates with the connection cache and responds to the server release request by marking the second connection as unused.

2. A system according to claim 1 wherein the opening apparatus responds to the server open request by re-using the first connection when the connection cache does contain information representing the first connection and the first connection is unused.

3. A system according to claim 2 wherein the opening apparatus marks the first connection as used when it re-uses the first connection.

4. A system according to claim 1 further comprising a clearing apparatus which responds to the server open request by selectively closing an open connection when the connection cache is full.

5. A system according to claim 4 wherein the clearing apparatus opens the first connection and stores information representing the first connection in the connection cache after selectively closing an open connection.

6. A system according to claim 1 further comprising a free list which stores information concerning all open and unused connections.

7. A system according to claim 6 wherein the opening apparatus responds to the server open request by checking the free list to determine whether the first connection is open and unused.

8. A system according to claim 6 wherein the releasing apparatus adds information representing the second connection to the free list.

9. A system according to claim 6 wherein the free list is implemented as a hash table.

10. A system according to claim 9 wherein the hash table is accessed by computing a hash value from connection information.

11. A method for managing connections between a server and a plurality of databases in a distributed object network in response to a server request to open a first connection and to a server request to release a second connection, the method comprising the steps of:

(a) storing information representing a plurality of connections;

(b) opening the first connection in response to the server open request and storing information representing the first connection in the connection cache when the connection cache does not already contain information representing the first connection; and

(c) marking the second connection as unused in response to the server release request.

12. A method according to claim 11 wherein step (a) comprises the step of:

(a1) re-using the first connection when the connection cache does contains information representing the first connection and the first connection is unused.

13. A method according to claim 12 wherein step (a1) further comprises the step of:

(a1a) marking the first connection as used.

14. A method according to claim 11 further comprising the step of:

2. selectively closing an open connection in response to the server open request when the connection cache is full.

15. A method according to claim 14 wherein step (d) further comprises the step of:

(d1) opening the first connection and storing information representing the first connection in the connection cache.

16. A method according to claim 11 further comprising the step of:

(e) storing information concerning all open and unused connections in a free list.

17. A method according to claim 16 wherein step (e) comprises the step of:

(e1) checking the free list in response to the server open request to determine whether the first connection is open and unused.

18. A method according to claim 16 wherein step (e) further comprises the step of:

(e2) adding information representing the second connection to the free list in response to the server release request.

19. A method according to claim 16 wherein the free list is implemented as a hash table.

20. A method according to claim 19 wherein step (e) further comprises the step of:

(e3) accessing the hash table by computing a hash value from connection information.

21. A computer program product for managing connections between a server and a plurality of databases in a distributed object network in response to a server request to open a first connection and to a server request to release a second connection, the computer program product comprising a computer usable medium having computer readable program code thereon, including:

program code for storing information representing a plurality of connections;

program code for opening the first connection in response to the server open request and storing information representing the first connection in the connection cache when the connection cache does not already contain information representing the first connection; and

program code for marking the second connection as unused in response to the server release request.

22. A computer program product according to claim 21 wherein the program code for storing information comprises program code for re-using the first connection when the connection cache does contains information representing the first connection and the first connection is unused.

23. A computer program product according to claim 22 wherein the program code for re-using the first connection comprises program code for marking the first connection as used.

24. A computer program product according to claim 21 further comprising program code for selectively closing an open connection in response to the server open request when the connection cache is full.