Support for schema evolution in a multi-node peer-to-peer replication environment

• US 20060190497A1
• Filed: 02/18/2005
• Published: 08/24/2006
• Est. Priority Date: 02/18/2005
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Inturi, Nagaraju, Pruet, Clarence Madison III
• Granted Patent: US 8,214,353 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/213 with details for schema evolution support
• CPC Class Codes: G06F 16/256 in federated or virtual databases

Abstract

A method, system and article of manufacture of replication are provided. A first replicate comprises a plurality of participants. The first replicate replicates one or more columns of a table. Replication data is transformed between a first local dictionary format and a first common dictionary format at a first participant of the plurality of participants. The replication data is transported in the first common dictionary format among the plurality of participants of the first replicate. The replication data is applied to a table on at least one other participant.

Claims

1. A method of replication, wherein a first replicate comprises a plurality of participants, said first replicate to replicate one or more columns of a table, comprising:

transforming replication data between a first local dictionary format and a first common dictionary format at a first participant of said plurality of participants;

transporting said replication data in said first common dictionary format among said plurality of participants; and

applying said replication data to said table on one or more other participants of said plurality of participants.

3. The method of claim 1 further comprising:

prior to altering said table at said first participant, notifying a replication application at that participant that said table is to be altered;

altering said table to provide said first local dictionary format; and

after altering said table, notifying said replication application at said first participant that said table was altered.

4. The method of claim 3 wherein in response to said notifying that said table is to be altered, said first participant suspends application of any replication data from said one or more other participants to said table.

5. The method of claim 3 further comprising:

in response to said notifying that said table was altered, reactivating said application of said any replication data from said one or more other participants to said table.

6. The method of claim 3 further comprising:

prior to said altering, advancing a replay position.

7. The method of claim 3 further comprising:

prior to said altering at said first participant,

suspending application of any replication data from said one or more other participants to said table;

determining a current position of writing change-data to a log; and

advancing a replay position to said current position.

8. The method of claim 7 further comprising:

after said altering, reactivating said application of any replication data from said one or more other participants to said table.

9. The method of claim 1 further comprising:

altering said table at each of said participants of said first replicate to provide an altered local dictionary format of said table at each of said participants, wherein said first local dictionary format is said altered local dictionary format; and

transforming replication data, on said one or more other participants, between said altered local dictionary format and said first common dictionary format.

10. The method of claim 9 further comprising:

creating a second replicate associated with said first replicate, said second replicate comprising said plurality of participants of said first replicate, said second replicate having a second common dictionary format based on said altered local dictionary format, wherein said applying treats said first and second replicates as equivalents.

11. The method of claim 1 wherein said first replicate is a mastered replicate.

12. The method of claim 10 wherein said first replicate is a primary mastered replicate, and said second replicate is a shadow mastered replicate.

13. The method of claim 12 further comprising:

swapping said first and second replicates such that said second replicate becomes a primary mastered replicate and said first replicate becomes a shadow mastered replicate.

2. The method of claim 2 further comprising:

transforming said replication data between said first common dictionary format and a second local dictionary format by at least one other participant of said other participants;

wherein said applying applies said replication data to a table on said at least one other participant based on said second local dictionary format.

14. An article of manufacture comprising a computer usable medium embodying one or more instructions executable by a computer for performing a method of replication, wherein a first replicate comprises a plurality of participants, said first replicate to replicate one or more columns of a table, said method comprising:

transforming replication data at a first participant of said plurality of participants between a first local dictionary format and a first common dictionary format;

sending said replication data in said first common dictionary format to one or more other participants of said plurality of participants;

receiving replication data in said first common dictionary format from at least one other participant of said plurality of participants;

transforming said replication data from said at least one other participant between said first common dictionary format and said first common dictionary format to provide transformed replication data; and

applying said transformed replication data to said table on said first participant.

15. The article of manufacture of claim 14 wherein said method further comprises:

prior to altering said table at said first participant,

notifying a replication application at said first participant that said table is to be altered;

altering said table to provide said first local dictionary format; and

after altering said table, notifying said replication application at said first participant that said table was altered.

16. The article of manufacture of claim 15 wherein said method further comprises:

in response to said notifying that said table is to be altered, said first participant suspends application of any replication data from said one or more other participants to said table.

17. The article of manufacture of claim 15 wherein said method further comprises:

in response to said notifying that said table was altered, reactivating said application of any replication data from said one or more other participants to said table.

18. The article of manufacture of claim 15 wherein said method further comprises:

prior to said altering, advancing a replay position.

19. The article of manufacture of claim 15 wherein said method further comprises:

prior to said altering at said first participant,

suspending application of any replication data from said one or more other participants to said table;

determining a current position of writing data to a log; and

advancing a replay position to said current position.

20. The article of manufacture of claim 19 wherein said method further comprises:

after said altering, reactivating said application of said any replication data from said one or more other participants to said table.

21. The article of manufacture of claim 20 wherein said method further comprises:

creating a second replicate associated with said first replicate, said second replicate comprising said plurality of participants of said first replicate, said second replicate having a second common dictionary format based on said first local dictionary format, wherein said applying treats said first and second replicates as equivalents.

22. The article of manufacture of claim 14 wherein said first replicate is a mastered replicate.

23. The article of manufacture of claim 21 wherein said first replicate is a primary mastered replicate, and said second replicate is a shadow mastered replicate.

24. The article of manufacture of claim 23 wherein said method further comprises:

swapping said first and second replicates such that said second replicate becomes a primary mastered replicate and said first replicate becomes a shadow mastered replicate.

25. A replication system, wherein a first replicate comprises a plurality of participants, said first replicate to replicate one or more columns of a table, comprising:

replication data which is transformed from a first local dictionary format to a first common dictionary format at a first participant of said plurality of participants at a first participant of said plurality of participants;

a queue that sends said replication data in said first common dictionary format to one or more other participants of said plurality of participants, wherein said queue also receives replication data in said first common dictionary format from at least one other participant of said plurality of participants to provide received replicated data;

said received replication data being transformed from said first common dictionary format to said first local dictionary format to provide transformed replication data; and

a table to which said transformed replication data has been applied.

26. The system of claim 25 further comprising:

a notification that said table is to be altered at said first participant;

said table being altered to provide said first local dictionary format; and

a notification that said table was altered.

27. The system of claim 26 wherein in response to said notification that said table is to be altered, application of any received replication data to said table is suspended at said first participant.

28. The system of claim 27 wherein in response to said notification that said table was altered, said application of said any received replication data to said table at said first participant is reactivated.

29. The system of claim 26 further comprising:

an advanced replay position.

30. The system claim 26 further comprising:

prior to said table being altered at said first participant,

application of any replication data to said table being suspended;

a current position of writing data to a log being determined; and

a replay position being advanced to said current position.

31. The system of claim 30 further comprising:

in response to said notification that said table is altered, said application of said any replication data to said table being reactivated at said first participant.

32. The system of claim 25 further comprising:

a second replicate associated with said first replicate, said second replicate comprising said plurality of participants of said first replicate, said second replicate having a second common dictionary format based on said first local dictionary format, and replication data being applied to said table such that said first and second replicates are equivalent.

33. The system of claim 25 wherein said first replicate is a mastered replicate.

34. The system of claim 32 wherein said first replicate is a primary mastered replicate, and said second replicate is a shadow mastered replicate.

35. The system of claim 32 wherein said first replicate and said second replicates are swapped such that said second replicate becomes a primary mastered replicate, and said first replicate becomes a shadow mastered replicate.