Bidirectional database replication scheme for controlling ping-ponging

• US 6,122,630 A
• Filed: 06/08/1999
• Issued: 09/19/2000
• Est. Priority Date: 06/08/1999
• Status: Expired due to Term

• Current Assignee: RPX Corporation
• Original Assignee: ITI Limited (Government of India)
• Inventors: Strickler, Gary E., Knapp, Herbert William, Holenstein, Bruce D., Holenstein, Paul J.
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): LE, UYEN T
• Application Number:
  US09/328,257
• Time in Patent Office: 469 Days
• Field of Search: 707/8, 707/1, 707/9, 707/10, 707/104, 707/201, 707/203, 707/204, 707/202, 709/208, 709/230, 709/232, 709/238, 714/1, 714/15, 714/20
• US Class Current: 1/1
• CPC Class Codes: G06F 16/27 Replication, distribution or synchronisation of data between databases or within a distributed database system; Distributed database system architectures therefor
• CPC Class Codes: Y10S 707/99938 Concurrency, e.g. lock management in shared database

Abstract

Transaction ping-pong is selectively prevented in a bidirectional database replication system. The system has a plurality of nodes connected via communication media in a topology. Each node includes a database and a transaction transmitter or collector which sends transactions posted to the database to a database at one or more other nodes for replication in the databases of the one or more other nodes. All transactions to be posted to databases in remote nodes that were sent by a local node are detected, and the database at the local node is inhibited from posting selective transactions which were detected as being originally sent by the local node.

Claims

1. A method of selectively preventing transaction ping-pong in a bidirectional database replication system including (i) a first database and (ii) a second database, the system further including (iii) a first transaction transmitter which sends transactions posted to the first database to the second database for replication in the second database, and (iv) a second transaction transmitter which sends transactions posted to the second database to the first database for replication in the first database only after the transactions are actually posted to the second database, each transaction being one or more transaction steps or transaction operations, the method comprising:

(a) detecting all transactions to be posted to the second database that were sent by the first transaction transmitter; and

(b) inhibiting the first database from posting selective transactions which were detected as being originally sent by the first transaction transmitter, wherein any transaction sent by the second transaction transmitter is replicated in the first database only after the transaction is actually posted to the second database.

2. A method according to claim 1 wherein the first database and the first transaction transmitter are at a first location, and the second database and the second transaction transmitter are at a second location remote from the first location, and the detecting step occurs at the second location.

3. A method according to claim 1 wherein the inhibiting step is performed by the second transaction transmitter which prevents the sending of selective transactions to the first database which were originally sent by the first transaction transmitter to the second database.

4. A method according to claim 1 wherein the system further includes (v) a first transaction receiver which receives transactions sent by the second transaction transmitter for posting to the first database, and (vi) a second transaction receiver which receives transactions sent by the first transaction transmitter for posting to the second database, the inhibiting step being performed by the first transaction receiver.

5. A method according to claim 4 wherein the first transaction transmitter is a first collector, the second transaction transmitter is a second collector, the first transaction receiver is a first consumer and the second transaction receiver is a second consumer.

6. A method according to claim 1 wherein the first and second databases define respective first and second tables of the same database located in the same physical location and the method allows for replication to the same database.

7. A method according to claim 1 wherein the first and second databases define respective first and second records of the same database located in the same physical location and the method allows for replication to the same database.

8. A method according to claim 1 wherein step (b) comprises inhibiting the first database from posting all transactions which were detected as being originally sent by the first transaction transmitter.

9. A method according to claim 1 further comprising:

(c) identifying transactions posted to the first database which should be returned to the first database for replication confirmation and transactions posted to the first database which should not be returned to the first database for replication confirmation, wherein the inhibiting step further comprises inhibiting the first database from posting only those transactions which were identified as those which should not be returned to the first database for replication confirmation.

10. A method according to claim 9 wherein the first database includes indicia of replication confirmation for each transaction identified in step (c) for which replication confirmation is desired, the method further comprising:

(d) posting a change to the replication confirmation indicia when posting transactions which were identified as those which should be returned to the first database.

11. A method according to claim 1 wherein the system further includes (v) a second transaction receiver which receives transactions sent by the first transaction transmitter for posting to the second database, (vi) a transaction log associated with the second database, and (vii) an audit trail of all transactions posted to the second database, the method further comprising:

(c) assigning a transaction identifier to every transaction received by the second transaction receiver which is posted to the second database;

(d) posting the transactions received by second transaction receiver in the second database and creating an audit trail of the posted transactions;

(e) storing the assigned transaction identifiers in the transaction log and associating the assigned transaction identifiers with the transactions in the audit trail; and

(f) the second transaction transmitter sending the transactions in the audit trail for posting to the first database,

wherein the detecting step (a) comprises detecting selective transactions in the audit trail which have a transaction identifier similar to a transaction identifier in the transaction log, and the inhibiting step (b) comprises inhibiting the first database from posting to the first database selective transactions in the audit trail which were detected as having a transaction identifier similar to a transaction identifier in the transaction log.

12. A method according to claim 11 wherein the inhibiting step (b) further comprises preventing the second transaction transmitter from sending to the first database selective transactions in the audit trail which were detected as having a transaction identifier similar to a transaction identifier in the transaction log.

13. A method according to claim 12 wherein the system further includes (viii) a first transaction receiver which receives transactions sent by the second transaction transmitter for posting to the first database, (ix) a transaction log associated with the first database, and (x) an audit trail of all transactions posted to the first database, the method further comprising:

(g) assigning a transaction identifier to every transaction received by the first transaction receiver which is posted to the first database;

(h) posting the transactions received by first transaction receiver in the first database and creating an audit trail of the transactions posted to the first database;

(i) storing the transaction identifiers assigned in step (g) in the transaction log associated with the first database and associating the transaction identifiers assigned in step (g) with the transactions in the audit trail of transactions posted to the first database;

(j) the first transaction transmitter sending the transactions in the audit trail of transactions posted to the first database for posting to the second database;

(k) detecting all transactions to be posted to the first database that were sent by the second transaction transmitter; and

(l) inhibiting the second database from posting selective transactions which were detected as being originally sent by the second transaction transmitter,

wherein the detecting step (k) comprises detecting selective transactions in the audit trail of transactions posted to the first database which have a transaction identifier similar to a transaction identifier in the transaction log associated with the first database, and the inhibiting step (1) comprises inhibiting the second database from posting to the second database selective transactions in the audit trail of transactions posted to the first database which were detected as having a transaction identifier similar to a transaction identifier in the transaction log associated with the first database.

14. A method according to claim 1 wherein the system further includes (v) a second transaction receiver which receives transactions sent by the first transaction transmitter for posting to the second database, (vi) a transaction log associated with the second database, and (vii) an audit trail of all transactions posted to the second database, the method further comprising:

(c) preassigning a block of unique transaction identifiers for transactions subsequently received by the second transaction receiver;

(d) storing the preassigned block of unique transaction identifiers in the audit trail and in the transaction log;

(e) assigning one of the preassigned unique transaction identifiers in the transaction log to each transaction subsequently received by the second transaction receiver;

(f) posting the transactions received by the second transaction receiver in the second database and creating an audit trail of the posted transactions, the audit trail including the assigned transaction identifiers; and

(g) the second transaction transmitter sending the transactions in the audit trail for posting to the first database,

wherein the detecting step (a) comprises detecting selective transactions in the audit trail which have a transaction identifier similar to a preassigned transaction identifier stored in the audit trail in step (d), and the inhibiting step (b) comprises inhibiting the first database from posting to the first database selective transactions in the audit trail which were detected as having a transaction identifier similar to a preassigned transaction identifier stored in the audit trail in step (d).

15. A method according to claim 14 wherein the inhibiting step (b) further comprises preventing the second transaction transmitter from sending to the first database selective transactions in the audit trail which were detected as having a transaction identifier similar to a preassigned transaction identifier stored in the audit trail in step (d).

16. A method according to claim 14 wherein steps (c) and (d) are repeated whenever the transaction log has assigned all of the previously preassigned unique transaction identifiers, the audit trail thereby containing all of the preassigned transaction identifiers.

17. A method according to claim 1 wherein the system further includes (v) a second transaction receiver which receives transactions sent by the first transaction transmitter, (vi) a second processor which posts the transactions received by the second transaction receiver to the second database, the second processor including a second processor identifier, and (vii) an audit trail of all transactions posted to the second database, the method further comprising:

(c) the second processor posting the transactions received by the second transaction receiver in the second database and creating an audit trail of the posted transactions, the audit trail including the second processor identifier; and

(d) the second transaction transmitter sending the transactions in the audit trail to the first database for posting to the first database,

wherein the detecting step (a) comprises detecting selective transactions which are in the audit trail of the second database and which include the second processor identifier, and the inhibiting step (b) comprises preventing the first database from posting selective transactions which were detected as being in the audit trail of the second database and which include the second processor identifier.

18. A method according to claim 17 wherein the inhibiting step (b) further comprises preventing the second transaction transmitter from sending to the first database selective transactions which are in the audit trail of the second database and which include the second processor identifier.

19. A method according to claim 17 further comprising:

(e) assigning a transaction identifier to every transaction received by the second transaction receiver which is posted to the second database, the transaction identifier including the second processor identifier; and

(f) storing the assigned transaction identifiers in the audit trail in association with the respective transactions,

wherein the inhibiting step (b) comprises preventing the first database from posting selective transactions which are in the audit trail of the second database and which include the second processor identifier as part of the transaction identifier.

20. A method according to claim 1 wherein the system further includes (v) a second transaction receiver which receives transactions sent by the first transaction transmitter, the second transaction receiver including a second transaction receiver identifier, and (vi) an audit trail of all transactions posted to the second database, the method further comprising:

(c) the second transaction receiver posting the transactions which it receives in the second database and creating an audit trail of the posted transactions, the audit trail including the second transaction receiver identifier; and

(d) the second transaction transmitter sending the transactions in the audit trail to the first database for posting to the first database,

wherein the detecting step (a) comprises detecting selective transactions which are in the audit trail of the second database and which include the second transaction receiver identifier, and the inhibiting step (b) comprises preventing the first database from posting a selective transactions which were detected as being in the audit trail of the second database and which include the second transaction receiver identifier.

21. A method according to claim 20 wherein the inhibiting step (b) further comprises preventing the second transaction transmitter from sending to the first database selective transactions which are in the audit trail of the second database and which include the second transaction receiver identifier.

22. A method according to claim 20 further comprising:

(e) assigning a transaction identifier to every transaction received by the second transaction receiver which is posted to the second database, the transaction identifier including the second transaction receiver identifier; and

(f) storing the assigned transaction identifiers in the audit trail in association with the respective transactions,

wherein the inhibiting step (b) comprises preventing the first database from posting selective transactions which are in the audit trail of the second database and which include the second transaction receiver identifier as part of the transaction identifier.

23. A method according to claim 1 wherein the system further includes (v) an audit trail of all transactions posted to the second database, the audit trail including a first audit trail containing all transactions posted to the second database which were sent by the first transaction transmitter, and a second audit trail containing all transactions posted to the second database which were not sent by the first transaction transmitter, the method further comprising:

(c) posting to the second database all transactions sent by the first transaction transmitter and creating an audit trail of the posted transactions in the first audit trail;

(d) posting to the second database all transactions not sent by the first transaction transmitter and creating an audit trail of the posted transactions in the second audit trail; and

(e) the second transaction transmitter sending the transactions in the audit trail to the first database for posting to the first database,

wherein the detecting step (a) comprises identifying selective transactions which are in the first audit trail of the second database, and the inhibiting step (b) comprises preventing the first database from posting selective transactions which were identified as being in the first audit trail of the second database.

24. A method according to claim 23 wherein the system further includes (vi) a second transaction receiver which receives transactions sent by the first transaction transmitter, wherein step (c) further includes the second transaction receiver posting the transactions which it receives in the second database and creating an audit trail of the posted transactions in the first audit trail;

and

wherein step (e) includes the second transaction transmitter sending the transactions in the audit trail to the first database for posting to the first database,

wherein the inhibiting step (b) comprises preventing the second transaction transmitter from sending to the first database selective transactions which are in the first audit trail of the second database.

25. A method according to claim 23 wherein the inhibiting step (b) further comprises preventing the second transaction transmitter from sending to the first database selective transactions which are in the first audit trail of the second database.

26. A method according to claim 23 wherein the audit trail is a single audit trail and the first and second audit trails are respective first and second parts of the single audit trail.

27. A method according to claim 1 wherein the system further includes (v) a second transaction receiver which receives transactions sent by the first transaction transmitter for posting to the second database, and (vi) an audit trail of all transactions posted to the second database, the method further comprising:

(c) posting the transactions received by the second transaction receiver in the second database and creating an audit trail of the posted transactions;

(d) communicating the transactions received by the second transaction receiver to the second transaction transmitter; and

(e) the second transaction transmitter sending the transactions in the audit trail to the first database for posting to the first database,

wherein the detecting step (a) comprises detecting selective transactions in the audit trail which were communicated to the second transaction transmitter in step (d), and the inhibiting step (b) comprises preventing the second transaction transmitter from sending to the first database selective transactions in the audit trail which were detected as being communicated to the second transaction transmitter.

28. A method according to claim 1 wherein each of the transactions include transaction data which is usable to identify the origin of the transaction, the system further including (v) an audit trail of all transactions posted to the second database, and (vi) application code which interprets the transaction data within posted transactions for identifying the origin of the transaction, thereby identifying the originally posted database of the transaction, the method further comprising:

(c) posting to the second database selective transactions sent by the first transaction transmitter and creating an audit trail of the posted transactions;

(d) the second transaction transmitter sending the transactions in the audit trail to the first database for posting to the first database; and

(e) executing the application code on all transactions read out of the audit trail for sending to the first database,

wherein the detecting step (a) comprises the application code identifying selective transactions which originated at the first database, and the inhibiting step (b) comprises preventing the first database from posting selective transactions which were identified by the application code as having originated at the first database.

29. A method according to claim 28 wherein the inhibiting step (b) further comprises preventing the second transaction transmitter from sending to the first database selective transactions which were identified by the application code as having originated at the first database.

30. A method of selectively preventing transaction ping-pong in a bidirectional database replication system including a plurality of nodes connected via communication media in a topology, each node including a database and a transaction transmitter which sends transactions posted to the database to a database at one or more other nodes for replication in the databases of the one or more other nodes only after the transactions are actually posted to the database of the sending node, each transaction being one or more transaction steps or transaction operations, the method comprising:

(a) detecting all transactions to be posted to databases in remote nodes that were sent by a local node; and

(b) inhibiting the database at the local node from posting selective transactions which were detected as being originally sent by the local node, wherein any transaction sent by a transaction transmitter of a node is replicated in the databases of the one or more other nodes only after the transaction is actually posted to the database of the sending node.

31. A method according to claim 30 wherein the transactions are stored within transaction records, the transaction records including indicia of how many nodes the transaction has replicated to, and step (b) )further includes inhibiting the database at the local node from posting selective transactions which were detected as being originally sent by the local node by virtue of having indicia that the transaction has replicated to a predetermined number of nodes.

32. A method according to claim 30 wherein each of the transactions include transaction data which is usable to identify the origin of the transaction, the system further including application code which interprets the transaction data within posted transactions for identifying the origin of the transaction, thereby identifying the originally posted database of the transaction, and step (b) further includes inhibiting the database at the local node from posting selective transactions which were detected as being originally sent by a node having a predetermined origin.

33. A method according to claim 30 wherein the inhibiting step is performed by a remote note which prevents the sending of any transactions to the local node which were detected as being originally sent by the local node to one or more remote nodes.

34. A system for selectively preventing transaction ping-pong in a bidirectional database replication system which includes a plurality of nodes connected via communication media in a topology, each node including a database and a transaction transmitter which sends transactions posted to the database to a database at one or more other nodes for replication in the databases of the one or more other nodes only after the transactions are actually posted to the database of the sending node, each transaction being one or more transaction steps or transaction operations, the system comprising:

(a) means for detecting all transactions to be posted to databases in remote nodes that were sent by a local node; and

(b) means for inhibiting the database at the local node from posting selective transactions which were detected as being originally sent by the local node, wherein any transaction sent by a transaction transmitter of a node is replicated in the databases of the one or more other nodes only after the transaction is actually posted to the database of the sending node.

35. A system according to claim 34 wherein the transactions are stored within transaction records, the transaction records including indicia of how many nodes the transaction has replicated to, and the means for inhibiting inhibits the database at the local node from posting selective transactions which were detected as being originally sent by the local node by virtue of having indicia that the transaction has replicated to a predetermined number of nodes.

65. A system according to claim 35 wherein each of the transactions include transaction data which is usable to identify the origin of the transaction, the bidirectional database replication system further including application code which interprets the transaction data within posted transactions for identifying the origin of the transaction, thereby identifying the originally posted database of the transaction, and the means for inhibiting inhibits the database at the local node from posting selective transactions which were detected as being originally sent by a node having a predetermined origin.

66. A system according to claim 34 wherein the inhibiting process is performed by a remote note which prevents the sending of any transactions to the local node which were detected as being originally sent by the local node to one or more remote nodes.

36. A system for selectively preventing transaction ping-pong in a bidirectional database replication system which includes (i) a first database and (ii) a second database, the system further including (iii) a first transaction transmitter which sends transactions posted to the first database to the second database for replication in the second database, and (iv) a second transaction transmitter which sends transactions posted to the second database to the first database for replication in the first database only after the transactions are actually posted to the second database, each transaction being one or more transaction steps or transaction operations, the system for selectively preventing transaction ping-pong comprising:

(a) means for detecting all transactions to be posted to the second database that were sent by the first transaction transmitter; and

(b) means for inhibiting the first database from posting selective transactions which were detected as being originally sent by the first transaction transmitter, wherein any transaction sent by the second transaction transmitter is replicated in the first database only after the transaction is actually posted to the second database.

37. A system according to claim 36 wherein the first database and the first transaction transmitter are at a first location, and the second database and the second transaction transmitter are at a second location remote from the first location, and the means for detecting is located at the second location.

38. A system according to claim 36 wherein the means for inhibiting is located in the second transaction transmitter, thereby preventing the sending of selective transactions to the first database which were originally sent by the first transaction transmitter to the second database.

39. A system according to claim 36 wherein the bidirectional database replication system further includes (v) a first transaction receiver which receives transactions sent by the second transaction transmitter for posting to the first database, and (vi) a second transaction receiver which receives transactions sent by the first transaction transmitter for posting to the second database, the means for inhibiting being located in the first transaction receiver.

40. A system according to claim 39 wherein the first transaction transmitter is a first collector, the second transaction transmitter is a second collector, the first transaction receiver is a first consumer and the second transaction receiver is a second consumer.

41. A system according to claim 36 wherein the first and second databases define respective first and second tables of the same database located in the same physical location and the system allows for replication to the same database.

42. A system according to claim 36 wherein the first and second databases define respective first and second records of the same database located in the same physical location and the system allows for replication to the same database.

43. A system according to claim 36 wherein the means for inhibiting inhibits the first database from posting all transactions which were detected as being originally sent by the first transaction transmitter.

44. A system according to claim 36 further comprising:

(c) means for identifying transactions posted to the first database which should be returned to the first database for replication confirmation and transactions posted to the first database which should not be returned to the first database for replication confirmation, wherein the means for inhibiting inhibits the first database from posting only those transactions which were identified as those which should not be returned to the first database for replication confirmation.

45. A system according to claim 44 wherein the first database includes indicia of replication confirmation for each transaction identified by the means for identifing for which replication confirmation is desired, the system further comprising:

(d) means for posting a change to the replication confirmation indicia when posting transactions which were identified as those which should be returned to the first database.

46. A system according to claim 36 wherein the bidirectional database replication system further includes (v) a second transaction receiver which receives transactions sent by the first transaction transmitter for posting to the second database, (vi) a transaction log associated with the second database, and (vii) an audit trail of all transactions posted to the second database, the system for selectively preventing transaction ping-pong further comprising:

(c) means for assigning a transaction identifier to every transaction received by the second transaction receiver which is posted to the second database;

(d) means for posting the transactions received by second transaction receiver in the second database and creating an audit trail of the posted transactions; and

(e) means for storing the assigned transaction identifiers in the transaction log and associating the assigned transaction identifiers with the transactions in the audit trail,

wherein the second transaction transmitter sends the transactions in the audit trail for posting to the first database,

and wherein the means for detecting detects selective transactions in the audit trail which have a transaction identifier similar to a transaction identifier in the transaction log, and the means for inhibiting inhibits the first database from posting to the first database selective transactions in the audit trail which were detected as having a transaction identifier similar to a transaction identifier in the transaction log.

47. A system according to claim 46 wherein the means for inhibiting prevents the second transaction transmitter from sending to the first database selective transactions in the audit trail which were detected as having a transaction identifier similar to a transaction identifier in the transaction log.

48. A system according to claim 47 wherein the bidirectional database replication system further includes (viii) a first transaction receiver which receives transactions sent by the second transaction transmitter for posting to the first database, (ix) a transaction log associated with the first database, and (x) an audit trail of all transactions posted to the first database, the first transaction transmitter sending the transactions in the audit trail of transactions posted to the first database for posting to the second database, the system for selectively preventing transaction ping-pong further comprising:

(f) means for assigning a transaction identifier to every transaction received by the first transaction receiver which is posted to the first database;

(g) means for posting the transactions received by first transaction receiver in the first database and creating an audit trail of the transactions posted to the first database;

(h) means for storing the assigned transaction identifiers in the transaction log associated with the first database and associating the transaction identifiers assigned by the means for assigning with the transactions in the audit trail of transactions posted to the first database;

(i) means for detecting all transactions to be posted to the first database that were sent by the second transaction transmitter; and

(j) means for inhibiting the second database from posting selective transactions which were detected as being originally sent by the second transaction transmitter,

wherein the means for detecting detects selective transactions in the audit trail of transactions posted to the first database which have a transaction identifier similar to a transaction identifier in the transaction log associated with the first database, and the means for inhibiting inhibits the second database from posting to the second database selective transactions in the audit trail of transactions posted to the first database which were detected as having a transaction identifier similar to a transaction identifier in the transaction log associated with the first database.

49. A system according to claim 36 wherein the bidirectional database replication system further includes (v) a second transaction receiver which receives transactions sent by the first transaction transmitter for posting to the second database, (vi) a transaction log associated with the second database, and (vii) an audit trail of all transactions posted to the second database, the second transaction transmitter sending the transactions in the audit trail for posting to the first database, the system for selectively preventing transaction ping-pong further comprising:

(c) means for preassigning a block of unique transaction identifiers for transactions subsequently received by the second transaction receiver;

(d) means for storing the preassigned block of unique transaction identifiers in the audit trail and in the transaction log;

(e) means for assigning one of the preassigned unique transaction identifiers in the transaction log to each transaction subsequently received by the second transaction receiver; and

(f) means for posting the transactions received by the second transaction receiver in the second database and creating an audit trail of the posted transactions, the audit trail including the assigned transaction identifiers;

wherein the means for detecting detects selective transactions in the audit trail which have a transaction identifier similar to a preassigned transaction identifier stored in the audit trail, and the means for inhibiting inhibits the first database from posting to the first database selective transactions in the audit trail which were detected as having a transaction identifier similar to a preassigned transaction identifier stored in the audit trail.

50. A system according to claim 49 wherein the means for inhibiting prevents the second transaction transmitter from sending to the first database selective transactions in the audit trail which were detected as having a transaction identifier similar to a preassigned transaction identifier stored in the audit trail.

51. A system according to claim 49 wherein the preassigning and storing processes performed by the means for preassigning and means for storing are repeated whenever the transaction log has assigned all of the previously preassigned unique transaction identifiers, the audit trail thereby containing all of the preassigned transaction identifiers.

52. A system according to claim 36 wherein the bidirectional database replication system further includes (v) a second transaction receiver which receives transactions sent by the first transaction transmitter, (vi) a second processor which posts the transactions received by the second transaction receiver to the second database, the second processor including a second processor identifier, and (vii) an audit trail of all transactions posted to the second database, the system for selectively preventing transaction ping-pong further comprising:

(c) means for posting the transactions received by the second transaction receiver in the second database and creating an audit trail of the posted transactions, the audit trail including the second processor identifier, the means for posting being located in the second processor;

wherein the second transaction transmitter sends the transactions in the audit trail to the first database for posting to the first database,

and wherein the means for detecting detects selective transactions which are in the audit trail of the second database and which include the second processor identifier, and the means for inhibiting comprises preventing the first database from posting selective transactions which were detected as being in the audit trail of the second database and which include the second processor identifier.

53. A system according to claim 52 wherein the means for inhibiting prevents the second transaction transmitter from sending to the first database selective transactions which are in the audit trail of the second database and which include the second processor identifier.

54. A system according to claim 52 further comprising:

(d) means for assigning a transaction identifier to every transaction received by the second transaction receiver which is posted to the second database, the transaction identifier including the second processor identifier; and

(e) means for storing the assigned transaction identifiers in the audit trail in association with the respective transactions,

wherein the means for inhibiting prevents the first database from posting selective transactions which are in the audit trail of the second database and which include the second processor identifier as part of the transaction identifier.

55. A system according to claim 36 wherein the bidirectional database replication system further includes (v) a second transaction receiver which receives transactions sent by the first transaction transmitter, the second transaction receiver including a second transaction receiver identifier, and (vi) an audit trail of all transactions posted to the second database, the system for selectively preventing transaction ping-pong further comprising:

(c) means for posting the transactions received by the second transaction receiver in the second database and creating an audit trail of the posted transactions, the audit trail including the second transaction receiver identifier,

wherein the second transaction transmitter sends the transactions in the audit trail to the first database for posting to the first database,

and wherein the means for detecting detects selective transactions which are in the audit trail of the second database and which include the second transaction receiver identifier, and the means for inhibiting prevents the first database from posting selective transactions which were detected as being in the audit trail of the second database and which include the second transaction receiver identifier.

56. A system according to claim 55 wherein the means for inhibiting prevents the second transaction transmitter from sending to the first database selective transactions which are in the audit trail of the second database and which include the second transaction receiver identifier.

57. A system according to claim 55 wherein the system for selectively preventing transaction ping-pong further comprises:

(d) means for assigning a transaction identifier to every transaction received by the second transaction receiver which is posted to the second database, the transaction identifier including the second transaction receiver identifier; and

(e) means for storing the assigned transaction identifiers in the audit trail in association with the respective transactions,

wherein the means for inhibiting prevents the first database from posting selective transactions which are in the audit trail of the second database and which include the second transaction receiver identifier as part of the transaction identifier.

58. A system according to claim 36 wherein the bidirectional database replication system further includes (v) an audit trail of all transactions posted to the second database, the audit trail including a first audit trail containing all transactions posted to the second database which were sent by the first transaction transmitter, and a second audit trail containing all transactions posted to the second database which were not sent by the first transaction transmitter, the system for selectively preventing transaction ping-pong further comprising:

(c) means for posting to the second database (i) all transactions sent by the first transaction transmitter and creating an audit trail of the posted transactions in the first audit trail, and (ii) all transactions not sent by the first transaction transmitter and creating an audit trail of the posted transactions in the second audit trail,

wherein the second transaction transmitter sends the transactions in the audit trail to the first database for posting to the first database,

and wherein the means for detecting comprises identifying selective transactions which are in the first audit trail of the second database, and the means for inhibiting prevents the first database from posting selective transactions which were identified as being in the first audit trail of the second database.

59. A system according to claim 58 wherein the bidirectional database replication system further includes (vi) a second transaction receiver which receives transactions sent by the first transaction transmitter and posts the transactions which it receives in the second database and creates an audit trail of the posted transactions in the first audit trail,

and wherein the second transaction transmitter sends the transactions in the audit trail to the first database for posting to the first database,

and wherein the means for inhibiting prevents the second transaction transmitter from sending to the first database selective transactions which are in the first audit trail of the second database.

60. A system according to claim 58 wherein the means for inhibiting prevents the second transaction transmitter from sending to the first database selective transactions which are in the first audit trail of the second database.

61. A system according to claim 58 wherein the audit trail is a single audit trail and the first and second audit trails are respective first and second parts of the single audit trail.

62. A system according to claim 36 wherein the bidirectional database replication system further includes (v) a second transaction receiver which receives transactions sent by the first transaction transmitter for posting to the second database, and (vi) an audit trail of all transactions posted to the second database, the system for selectively preventing transaction ping-pong further comprising:

(c) means for posting the transactions received by the second transaction receiver in the second database and creating an audit trail of the posted transactions; and

(d) means for communicating the transactions received by the second transaction receiver to the second transaction transmitter,

wherein the second transaction transmitter sends the transactions in the audit trail to the first database for posting to the first database,

and wherein the means for detecting comprises detecting selective transactions in the audit trail which were communicated to the second transaction transmitter, and the means for inhibiting comprises preventing the second transaction transmitter from sending to the first database selective transactions in the audit trail which were detected as being communicated to the second transaction transmitter.

63. A system according to claim 36 wherein each of the transactions include transaction data which is usable to identify the origin of the transaction, the bidirectional database replication system further including (v) an audit trail of all transactions posted to the second database, and (vi) application code which interprets the transaction data within posted transactions for identifying the origin of the transaction, thereby identifying the originally posted database of the transaction, the system for selectively preventing transaction ping-pong firer comprising

(c) means for posting to the second database selective transactions sent by the first transaction transmitter and creating an audit trail of the posted transactions, wherein the second transaction transmitter sends the transactions in the audit trail to the first database for posting to the first database;

and

(e) means for executing the application code on all transactions read out of the audit trail for sending to the first database,

wherein the means for detecting uses the application code to identify selective transactions which originated at the first database, and the means for inhibiting prevents the first database from posting selective transactions which were identified by the application code as having originated at the first database.

64. A system according to claim 63 wherein the means for inhibiting prevents the second transaction transmitter from sending to the first database selective transactions which were identified by the application code as having originated at the first database.

67. An article of manufacture comprising a computer usable medium having computer readable code means therein for selectively preventing transaction ping-pong in a bidirectional database replication system which includes a plurality of nodes connected via communication media in a topology, each node including a database and a transaction transmitter which sends transactions posted to the database to a database at one or more other nodes for replication in the databases of the one or more other nodes only after the transactions are actually posted to the database of the sending node, each transaction being one or more transaction steps or transaction operations, the computer readable program code means in the article of manufacture comprising:

(a) computer readable program code means for detecting all transactions to be posted to databases in remote nodes that were sent by a local node; and

(b) computer readable program code means for inhibiting the database at the local node from posting selective transactions which were detected as being originally sent by the local node, wherein any transaction sent by a transaction transmitter of a node is replicated in the databases of the one or more other nodes only after the transaction is actually posted to the database of the sending node.

68. An article of manufacture according to claim 67 wherein the transactions are stored within transaction records, the transaction records including indicia of how many nodes the transaction has replicated to, and the computer readable program code means for inhibiting inhibits the database at the local node from posting selective transactions which were detected as being originally sent by the local node by virtue of having indicia that the transaction has replicated to a predetermined number of nodes.

69. An article of manufacture according to claim 68 wherein each of the transactions include transaction data which is usable to identify the origin of the transaction, the bidirectional database replication system further including application code which interprets the transaction data within posted transactions for identifying the origin of the transaction, thereby identifying the originally posted database of the transaction, and the computer readable program code means for inhibiting inhibits the database at the local node from posting selective transactions which were detected as being originally sent by a node having a predetermined origin.

70. An article of manufacture according to claim 67 wherein the inhibiting process is performed by a remote note which prevents the sending of any transactions to the local node which were detected as being originally sent by the local node to one or more remote nodes.

71. An article of manufacture comprising a computer usable medium having computer readable code means therein for selectively preventing transaction ping-pong in a bidirectional database replication system, the system including (i) a first database and (ii) a second database, the system further including (iii) a first transaction transmitter which sends transactions posted to the first database to the second database for replication in the second database, and (iv) a second transaction transmitter which sends transactions posted to the second database to the first database for replication in the first database only after the transactions are actually posted to the second database, each transaction being one or more transaction steps or transaction operations, the computer readable program code means in the article of manufacture comprising:

(a) computer readable program code means for detecting all transactions to be posted to the second database that were sent by the first transaction transmitter; and

(b) computer readable program code means for inhibiting the first database from posting selective transactions which were detected as being originally sent by the first transaction transmitter, wherein any transaction sent by the second transaction transmitter is replicated in the first database only after the transaction is actually posted to the second database.

72. An article of manufacture according to claim 71 wherein the first database and the first transaction transmitter are at a first location, and the second database and the second transaction transmitter are at a second location remote from the first location, and the computer readable program code means for detecting is located at the second location.

73. An article of manufacture according to claim 71 wherein the computer readable program code means for inhibiting is located in the second transaction transmitter, thereby preventing the sending of selective transactions to the first database which were originally sent by the first transaction transmitter to the second database.

74. An article of manufacture according to claim 71 wherein the bidirectional database replication system further includes (v) a first transaction receiver which receives transactions sent by the second transaction transmitter for posting to the first database, and (vi) a second transaction receiver which receives transactions sent by the first transaction transmitter for posting to the second database, the computer readable program code means for inhibiting being located in the first transaction receiver.

75. An article of manufacture according to claim 74 wherein the first transaction transmitter is a first collector, the second transaction transmitter is a second collector, the first transaction receiver is a first consumer and the second transaction receiver is a second consumer.

76. An article of manufacture according to claim 71 wherein the first and second databases define respective first and second tables of the same database located in the same physical location and the system allows for replication to the same database.

77. An article of manufacture according to claim 71 wherein the first and second databases define respective first and second records of the same database located in the same physical location and the system allows for replication to the same database.

78. An article of manufacture according to claim 71 wherein the computer readable program code means for inhibiting inhibits the first database from posting all transactions which were detected as being originally sent by the first transaction transmitter.

79. An article of manufacture according to claim 71 wherein the computer readable code means in the article of manufacture further comprises:

(c) computer readable program code means for identifying transactions posted to the first database which should be returned to the first database for replication confirmation and transactions posted to the first database which should not be returned to the first database for replication confirmation, wherein the computer readable program code means for inhibiting inhibits the first database from posting only those transactions which were identified as those which should not be returned to the first database for replication confirmation.

80. An article of manufacture according to claim 79 wherein the first database includes indicia of replication confirmation for each transaction identified by the computer readable program code means for identifying for which replication confirmation is desired, wherein the computer readable code means in the article of manufacture further comprises:

(d) computer readable program code means for posting a change to the replication confirmation indicia when posting transactions which were identified as those which should be returned to the first database.

81. An article of manufacture according to claim 71 wherein the bidirectional database replication system further includes (v) a second transaction receiver which receives transactions sent by the first transaction transmitter for posting to the second database, (vi) a transaction log associated with the second database, and (vii) an audit trail of all transactions posted to the second database, the computer readable code means in the article of manufacture further comprising:

(c) computer readable program code means for assigning a transaction identifier to every transaction received by the second transaction receiver which is posted to the second database;

(d) computer readable program code means for posting the transactions received by second transaction receiver in the second database and creating an audit trail of the posted transactions; and

(e) computer readable program code means for storing the assigned transaction identifiers in the transaction log and associating the assigned transaction identifiers with the transactions in the audit trail,

wherein the second transaction transmitter sends the transactions in the audit trail for posting to the first database,

and wherein the computer readable program code means for detecting detects selective transactions in the audit trail which have a transaction identifier similar to a transaction identifier in the transaction log, and the computer readable program code means for inhibiting inhibits the first database from posting to the first database selective transactions in the audit trail which were detected as having a transaction identifier similar to a transaction identifier in the transaction log.

82. An article of manufacture according to claim 81 wherein the computer readable program code means for inhibiting prevents the second transaction transmitter from sending to the first database selective transactions in the audit trail which were detected as having a transaction identifier similar to a transaction identifier in the transaction log.

83. An article of manufacture according to claim 82 wherein the bidirectional database replication system further includes (viii) a first transaction receiver which receives transactions sent by the second transaction transmitter for posting to the first database, (ix) a transaction log associated with the first database, and (x) an audit trail of all transactions posted to the first database, the first transaction transmitter sending the transactions in the audit trail of transactions posted to the first database for posting to the second database, the computer readable code means in the article of manufacture further comprising:

(f) computer readable program code means for assigning a transaction identifier to every transaction received by the first transaction receiver which is posted to the first database;

(g) computer readable program code means for posting the transactions received by first transaction receiver in the first database and creating an audit trail of the transactions posted to the first database;

(h) computer readable program code means for storing the assigned transaction identifiers in the transaction log associated with the first database and associating the transaction identifiers assigned by the computer readable program code means for assigning with the transactions in the audit trail of transactions posted to the first database;

(i) computer readable program code means for detecting all transactions to be posted to the first database that were sent by the second transaction transmitter; and

(j) computer readable program code means for inhibiting the second database from posting selective transactions which were detected as being originally sent by the second transaction transmitter,

wherein the computer readable program code means for detecting detects selective transactions in the audit trail of transactions posted to the first database which have a transaction identifier similar to a transaction identifier in the transaction log associated with the first database, and the computer readable program code means for inhibiting inhibits the second database from posting to the second database selective transactions in the audit trail of transactions posted to the first database which were detected as having a transaction identifier similar to a transaction identifier in the transaction log associated with the first database.

84. An article of manufacture according to claim 71 wherein the bidirectional database replication system further includes (v) a second transaction receiver which receives transactions sent by the first transaction transmitter for posting to the second database, (vi) a transaction log associated with the second database, and (vii) an audit trail of all transactions posted to the second database, the second transaction transmitter sending the transactions in the audit trail for posting to the first database, the computer readable code means in the article of manufacture further comprising:

(c) computer readable program code means for preassigning a block of unique transaction identifiers for transactions subsequently received by the second transaction receiver;

(d) computer readable program code means for storing the preassigned block of unique transaction identifiers in the audit trail and in the transaction log;

(e) computer readable program code means for assigning one of the preassigned unique transaction identifiers in the transaction log to each transaction subsequently received by the second transaction receiver; and

(f) computer readable program code means for posting the transactions received by the second transaction receiver in the second database and creating an audit trail of the posted transactions, the audit trail including the assigned transaction identifiers;

wherein the computer readable program code means for detecting detects selective transactions in the audit trail which have a transaction identifier similar to a preassigned transaction identifier stored in the audit trail, and the computer readable program code means for inhibiting inhibits the first database from posting to the first database selective transactions in the audit trail which were detected as having a transaction identifier similar to a preassigned transaction identifier stored in the audit trail.

85. An article of manufacture according to claim 84 wherein the computer readable program code means for inhibiting prevents the second transaction transmitter from sending to the first database selective transactions in the audit trail which were detected as having a transaction identifier similar to a preassigned transaction identifier stored in the audit trail.

86. An article of manufacture according to claim 84 wherein the preassigning and storing processes performed by the computer readable program code means for preassigning and computer readable program code means for storing are repeated whenever the transaction log has assigned all of the previously preassigned unique transaction identifiers, the audit trail thereby containing all of the preassigned transaction identifiers.

87. An article of manufacture according to claim 71 wherein the bidirectional database replication system further includes (v) a second transaction receiver which receives transactions sent by the first transaction transmitter, (vi) a second processor which posts the transactions received by the second transaction receiver to the second database, the second processor including a second processor identifier, and (vii) an audit trail of all transactions posted to the second database, the computer readable code means in the article of manufacture further comprising:

(c) computer readable program code means for posting the transactions received by the second transaction receiver in the second database and creating an audit trail of the posted transactions, the audit trail including the second processor identifier, the computer readable program code means for posting being located in the second processor;

wherein the second transaction transmitter sends the transactions in the audit trail to the first database for posting to the first database,

and wherein the computer readable program code means for detecting detects selective transactions which are in the audit trail of the second database and which include the second processor identifier, and the computer readable program code means for inhibiting comprises preventing the first database from posting selective transactions which were detected as being in the audit trail of the second database and which include the second processor identifier.

88. An article of manufacture according to claim 87 wherein the computer readable program code means for inhibiting prevents the second transaction transmitter from sending to the first database selective transactions which are in the audit trail of the second database and which include the second processor identifier.

89. An article of manufacture according to claim 87 further comprising:

(d) computer readable program code means for assigning a transaction identifier to every transaction received by the second transaction receiver which is posted to the second database, the transaction identifier including the second processor identifier; and

(e) computer readable program code means for storing the assigned transaction identifiers in the audit trail in association with the respective transactions,

wherein the computer readable program code means for inhibiting prevents the first database from posting selective transactions which are in the audit trail of the second database and which include the second processor identifier as part of the transaction identifier.

90. An article of manufacture according to claim 71 wherein the bidirectional database replication system further includes (v) a second transaction receiver which receives transactions sent by the first transaction transmitter, the second transaction receiver including a second transaction receiver identifier, and (vi) an audit trail of all transactions posted to the second database, the computer readable code means in the article of manufacture further comprising:

(c) computer readable program code means for posting the transactions received by the second transaction receiver in the second database and creating an audit trail of the posted transactions, the audit trail including the second transaction receiver identifier,

wherein the second transaction transmitter sends the transactions in the audit trail to the first database for posting to the first database,

and wherein the computer readable program code means for detecting detects selective transactions which are in the audit trail of the second database and which include the second transaction receiver identifier, and the computer readable program code means for inhibiting prevents the first database from posting selective transactions which were detected as being in the audit trail of the second database and which include the second transaction receiver identifier.

91. An article of manufacture according to claim 90 wherein the computer readable program code means for inhibiting prevents the second transaction transmitter from sending to the first database selective transactions which are in the audit trail of the second database and which include the second transaction receiver identifier.

92. An article of manufacture according to claim 90 further comprising:

(d) computer readable program code means for assigning a transaction identifier to every transaction received by the second transaction receiver which is posted to the second database, the transaction identifier including the second transaction receiver identifier; and

(e) computer readable program code means for storing the assigned transaction identifiers in the audit trail in association with the respective transactions,

wherein the computer readable program code means for inhibiting prevents the first database from posting selective transactions which are in the audit trail of the second database and which include the second transaction receiver identifier as part of the transaction identifier.

93. An article of manufacture according to claim 71 wherein the bidirectional database replication system further includes (v) an audit trail of all transactions posted to the second database, the audit trail including a first audit trail containing all transactions posted to the second database which were sent by the first transaction transmitter, and a second audit trail containing all transactions posted to the second database which were not sent by the first transaction transmitter, the computer readable code means in the article of manufacture further comprising:

(c) computer readable program code means for posting to the second database (i) all transactions sent by the first transaction transmitter and creating an audit trail of the posted transactions in the first audit trail, and (ii) all transactions not sent by the first transaction transmitter and creating an audit trail of the posted transactions in the second audit trail,

wherein the second transaction transmitter sends the transactions in the audit trail to the first database for posting to the first database,

and wherein the computer readable program code means for detecting comprises identifying selective transactions which are in the first audit trail of the second database, and the computer readable program code means for inhibiting prevents the first database from posting selective transactions which were identified as being in the first audit trail of the second database.

94. An article of manufacture according to claim 93 wherein the bidirectional database replication system further includes (vi) a second transaction receiver which receives transactions sent by the first transaction transmitter and posts the transactions which it receives in the second database and creates an audit trail of the posted transactions in the first audit trail,

and wherein the second transaction transmitter sends the transactions in the audit trail to the first database for posting to the first database,

and wherein the computer readable program code means for inhibiting prevents the second transaction transmitter from sending to the first database selective transactions which are in the first audit trail of the second database.

95. An article of manufacture according to claim 93 wherein the computer readable program code means for inhibiting prevents the second transaction transmitter from sending to the first database selective transactions which are in the first audit trail of the second database.

96. An article of manufacture according to claim 93 wherein the audit trail is a single audit trail and the first and second audit trails are respective first and second parts of the single audit trail.

97. An article of manufacture according to claim 71 wherein the bidirectional database replication system further includes (v) a second transaction receiver which receives transactions sent by the first transaction transmitter for posting to the second database, and (vi) an audit trail of all transactions posted to the second database, the computer readable code means in the article of manufacture further comprising:

(c) computer readable program code means for posting the transactions received by the second transaction receiver in the second database and creating an audit trail of the posted transactions; and

(d) computer readable program code means for communicating the transactions received by the second transaction receiver to the second transaction transmitter,

wherein the second transaction transmitter sends the transactions in the audit trail to the first database for posting to the first database,

and wherein the computer readable program code means for detecting comprises detecting selective transactions in the audit trail which were communicated to the second transaction transmitter, and the computer readable program code means for inhibiting comprises preventing the second transaction transmitter from sending to the first database selective transactions in the audit trail which were detected as being communicated to the second transaction transmitter.

98. An article of manufacture according to claim 71 wherein each of the transactions include transaction data which is usable to identify the origin of the transaction, the bidirectional database replication system further including (v) an audit trail of all transactions posted to the second database, and (vi) application code which interprets the transaction data within posted transactions for identifying the origin of the transaction, thereby identifying the originally posted database of the transaction, the computer readable code means in the article of manufacture further comprising:

(c) computer readable program code means for posting to the second database selective transactions sent by the first transaction transmitter and creating an audit trail of the posted transactions, wherein the second transaction transmitter sends the transactions in the audit trail to the first database for posting to the first database; and

(e) computer readable program code means for executing the application code on all transactions read out of the audit trail for sending to the first database,

wherein the computer readable program code means for detecting uses the application code to identify selective transactions which originated at the first database, and the computer readable program code means for inhibiting prevents the first database from posting selective transactions which were identified by the application code as having originated at the first database.

99. An article of manufacture according to claim 98 wherein the computer readable program code means for inhibiting prevents the second transaction transmitter from sending to the first database selective transactions which were identified by the application code as having originated at the first database.