Dynamic synchronization of tables

• US 7,363,332 B2
• Filed: 03/04/2003
• Issued: 04/22/2008
• Est. Priority Date: 06/29/1999
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Berkowitz, Brian T., Christofferson, Peter A.
• Primary Examiner(s): PHAM, HUNG Q
• Application Number:
  US10/379,605
• Publication Number:
  US 20030172054A1
• Time in Patent Office: 1,876 Days
• Field of Search: 707/101, 707/102, 707/200, 707/204, 707/10, 707/1
• US Class Current: 707/639
• CPC Class Codes: G06F 16/273 Asynchronous replication or reconciliation
• CPC Class Codes: Y10S 707/99931 Database or file accessing
• CPC Class Codes: Y10S 707/99936 Pattern matching access
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users
• CPC Class Codes: Y10S 707/99953 Recoverability
• CPC Class Codes: Y10S 707/99955 Archiving or backup

Abstract

Each node in a network accessing a common database caches a copy of the database tables it uses and updates those tables based on changes made by other nodes in a coherent cache, i.e., those node that also have a copy of the tables in their cache. When a new node joins the coherent cache, dynamic synchronization of the table is performed by having one of the existing nodes act as a source to populate the table(s) required on the new (destination) node from its own copy. The dynamic synchronization controls the population operation and allows for the populating of tables on the destination node from partially populated tables on the source node. The dynamic synchronization of the tables permits database updates to continue to be made to the tables by the existing nodes in the coherent cache and provides a mechanism to propagate the committed updates to the tables on the destination node. Once the tables on the destination node are fully populated, all pending updates are suspended while a snapshot of the state of the table on the source node is taken. Once the destination node has processed the snapshot, active transactions on the source node are initiated on the destination node, and all transactions are allowed to modify the table on the destination node.

Claims

1. A computer-readable medium having stored thereon instructions, which, when executed by a computer, cause the computer to perform a method of synchronizing a table, wherein the method comprises:

streaming, to a destination node, a data stream for a table of a source node, wherein the data stream comprises;

static data for the table;

a first end-of-stream message;

snapshot data for the table comprising uncommitted changes associated with active transactions which are currently in progress on the source node, wherein active transactions involve the table;

an end-of-snapshot message; and

a second end-of stream message;

creating, on the destination node, a copy of the table from the static data;

before streaming snapshot data, pausing, on the source node, the active transactions;

after streaming snapshot data, resuming, on the source node, the active transactions corresponding to the associated uncommitted changes that have been sent to the destination node; and

initiating, on the destination node, active transactions that correspond to initialize-remote-transaction messages sent from the source node.

2. The computer-readable medium of claim 1, wherein the static data comprises:

metadata for the table; and

record data for the table.

3. The computer-readable medium of claim 1, wherein the data stream further comprises:

committed changes to the table interspersed with the static data.

4. The computer-readable medium of claim 1, wherein the snapshot data further comprises:

committed changes interspersed with the uncommitted changes.

5. A computer-readable medium having stored thereon instructions which, when executed by a computer, cause the computer to perform a control stream utilized in a method of synchronizing a table, wherein the method comprises:

streaming, to a destination node, static data for a table of a source node;

streaming, to the destination node, snapshot data for the table comprising uncommitted changes associated with active transactions which are currently in progress on the source node, wherein active transactions involve the table;

creating, on the destination node, a copy of the table from the static data and the committed changes;

before sending the snapshot data, pausing the active transactions;

resuming, on the source node, the active transactions when the snapshot data has been sent to the destination node;

streaming a control stream for synchronizing the table of the source node with the created table on the destination node, the control stream comprising;

an end-of-snapshot-response message;

an initialize-remote-transaction message for each active transaction; and

an initialize-remote-transaction-response message for each initialize-remote-transaction message; and

initiating, on the destination node, remote transactions that correspond to initialize-remote-transaction messages.

6. The computer-readable medium of claim 5, wherein the control stream further comprises:

an end-of-snapshot-transaction message.

7. The computer-readable medium of claim 6, wherein the end-of-snapshot-transaction message comprises:

an identifier for a terminated transaction.

8. The computer-readable medium of claim 5, wherein the control stream further comprises:

an end-of-synchronization message; and

an end-of-synchronization-response message.

9. In a computer system, a method of synchronizing a table, the method comprising:

sending a data stream for a table from a source node, wherein the data stream comprises;

static data for the table;

a first end-of-stream message;

snapshot data for the table, the snapshot data comprising uncommitted changes associated with active transactions which are currently in progress on the source node, wherein active transaction involve the table;

an end-of-snapshot message; and

a second end-of stream message;

creating on the destination node, a copy of the table from the static data;

before sending snapshot data, pausing, on the source node the active transactions;

after sending snapshot data, resuming, on the source node, the active transactions corresponding to the associated uncommitted changes that have been sent to the destination node; and

initiating, on the destination node, active transactions that correspond to initialize-remote-transaction messages sent from the source node.

10. The method of claim 9 wherein the static data for the table comprises:

metadata for the table; and

record data for the table.

11. The method of claim 9 wherein the data stream further comprises committed changes to the table interspersed with the static data.

12. The method of claim 9 wherein the snapshot data further comprises committed changes interspersed with the uncommitted changes.

13. In a computer system, a method of synchronizing a table, the method comprising:

streaming, to a destination node, static data for a table of a source node;

streaming to the destination node, snapshot data for the table comprising uncommitted changes associated with active transactions which are currently in progress on the source node, wherein active transactions involve the table;

creating, on the destination node, a copy of the table from the static data and committed changes;

before sending the snapshot data, pausing, on the source node, active transactions that involve the table;

resuming, on the source node, the active transactions when the snapshot data has been sent to the destination node;

streaming a control stream for synchronizing the table of the source node with the created table on the destination node, the control stream comprising;

an end-of-snapshot-response message;

an initialize-remote-transaction message for each active transaction; and

an initialize-remote-transaction-response message for each initialize-remote-transaction message; and

initiating, on the destination node, remote transactions that correspond to initialize-remote-transaction messages.

14. The method of claim 13 wherein the control stream further comprises an end-of-snapshot-transaction message.

15. The method of claim 14 wherein the end-of-snapshot-transaction message comprises an identifier for a terminated transaction.

16. The method of claim 13 wherein the control stream further comprises:

an end-of synchronization message; and

an end-of-synchronization-response message.

17. A computer system for synchronizing a table comprising:

a source node computer coupled to a network; and

a destination node computer coupled to the network;

a computer program executed by the computer system for;

streaming, to the destination node computer, a data stream for a table of the source node computer, wherein the data stream comprises;

static data for the table;

a first end-of-stream message;

snapshot data for the table comprising uncommitted changes associated with active transactions which are currently in progress on the source node, wherein active transactions involve the table;

an end-of-snapshot message; and

a second end-of stream message;

creating, on the destination node, a copy of the table from the static data;

before streaming snapshot data, pausing, on the source node, the active transactions;

after streaming snapshot data, resuming, on the source node, the active transactions corresponding to the associated uncommitted changes have been sent to the destination node; and

initiating, on the destination node, active transactions that correspond to initialize remote transaction messages sent from the source node.

18. The computer system of claim 17 wherein the communication medium is also for sending a control stream for synchronizing a table between the source node and the destination node, and wherein the control stream comprises:

an end-of-snapshot-response message;

an initialize-remote-transaction message; and

an initialize-remote-transaction-response message.