Transactional replication
View Patent ↗Writing data in a distributed database having a plurality of nodes is disclosed. Writing includes receiving a write request at a node, wherein the write request is associated with one or more operations to define an atomic transaction and performing the atomic transaction based on the request. The atomic transaction includes writing to a first version of the database in the node and writing to an entity representative of a state of the first version of the database.
1. A method of writing data in a distributed database having a plurality of nodes, comprising:
receiving a write request at a first member node having a first version of a database;
applying the received original write request to both the first version of the database and a journal queue in a single atomic transaction using a processor, comprising:
placing the received write request in the journal, queue of the first member node, wherein the journal queue is associated with the first member node and is configured to store write requests that have not yet been reconciled with a master version of the database on a master node;
propagating one or more items in the journal queue to the master node;
determining whether a conflict exists between the first version of the database with the write request applied and a master version of the database;
in the event that a conflict exists, reconciling a write request with the master version of the database; and
in the event that a conflict does not exist:
determining that the first version of the database is in a high availability pair, wherein the high availability pair includes a second version of the database in a second member node; and
applying the received original write request to both the first version of the database and to the second version of the database in the second member node.
2. The method of claim 1 , wherein the write request comprises a semantically expressed request to modify the database without sending changed data.
3. The method of claim 1 , wherein the write request includes one or more selected from the group consisting of commands, operations, and instructions.
4. The method of claim 1 , wherein the first member node is an active node and the second member node is a passive node in the high availability pair.
5. The method of claim 1 , wherein the second member node is associated with a second journal queue and further including applying the write request to the second version of the database and to the second journal queue in a single atomic transaction.
6. The method of claim 1 , further comprising:
receiving from the master node an indication that the one or more items in the journal queue have been reconciled with the master version of the database by the master node.
7. The method of claim 1 , further comprising:
receiving from the master node an indication that the one or more items in the journal queue have been reconciled with the master version of the database by the master node; and
in response to receiving the indication, removing the one or more items from the journal queue.
8. The method of claim 1 , further comprising:
receiving from the master node an indication that the one or more items in the journal queue have been reconciled with the master version of the database by the master node, wherein the indication indicates whether data in the master version of the database conflicts with the one or more items in the journal queue.
9. The method of claim 1 , further comprising:
receiving from the master node an indication that the one or more items in the journal queue have been reconciled with the master version of the database by the master node; and
in the event that the indication indicates a conflict between data in the master version of the database and the one or more items in the journal queue, resolving the conflict.
10. The method of claim 1 , further comprising:
receiving from the master node an indication that the one or more items in the journal queue have been reconciled with the master version of the database by the master node; and
in the event that the indication indicates a conflict between data in the master version of the database and the one or more items in the journal queue, resolving the conflict, wherein removing the one or more items from the journal queue and resolving the conflict are performed in a single atomic transaction.
11. A computer program product for writing data in a distributed database having a plurality of nodes, the computer program product being embodied in a tangible computer readable storage medium and comprising computer instructions for:
receiving a write request at a first member node having a first version of a database;
applying the received original write request to both the first version of the database and a journal queue in a single atomic transaction, comprising:
placing the write request in the journal, queue of the first member node, wherein the journal queue is associated with the first member node and is configured to store write requests that have not yet been reconciled with a master version of the database on a master node;
propagating one or more items in the journal queue to the master node;
determining whether a conflict exists between the first version of the database with the write request applied and a master version of the database;
in the event that a conflict exists, reconciling a write request with the master version of the database; and
in the event that a conflict does not exist:
determining that the first version of the database is in a high availability pair, wherein the high availability pair includes a second version of the database in a second member node; and
applying the received original write request to both the first version of the database and to the second version of the database in the second member node.
12. The computer program product recited in claim 11 , wherein the write request comprises a semantically expressed request to modify the database without sending changed data.
13. The computer program product recited in claim 11 , wherein the write request includes one or more selected from the group consisting of commands, operations, and instructions.
14. The computer program product recited in claim 11 , wherein the first member node is an active node and the second member node is a passive node in the high availability pair.
15. The computer program product recited in claim 11 , wherein the second member node is associated with a second journal queue and further including applying the write request to the second version of the database and to the second journal queue in a single atomic transaction.
16. The computer program product recited in claim 11 , further comprising computer instructions for:
receiving from the master node an indication that the one or more items in the journal queue have been reconciled with the master version of the database by the master node.
17. The computer program product recited in claim 11 , further comprising computer instructions for:
receiving from the master node an indication that the one or more items in the journal queue have been reconciled with the master version of the database by the master node; and
in response to receiving the indication, removing the one or more items from the journal queue.
18. The computer program product recited in claim 11 , further comprising computer instructions for:
receiving from the master node an indication that the one or more items in the journal queue have been reconciled with the master version of the database by the master node, wherein the indication indicates whether data in the master version of the database conflicts with the one or more items in the journal queue.
19. The computer program product recited in claim 11 , further comprising computer instructions for:
receiving from the master node an indication that the one or more items in the journal queue have been reconciled with the master version of the database by the master node; and
in the event that the indication indicates a conflict between data in the master version of the database and the one or more items in the journal queue, resolving the conflict.
20. The computer program product recited in claim 11 , further comprising computer instructions for:
receiving from the master node an indication that the one or more items in the journal queue have been reconciled with the master version of the database by the master node; and
in the event that the indication indicates a conflict between data in the master version of the database and the one or more items in the journal queue, resolving the conflict, wherein removing the one or more items from the journal queue and resolving the conflict are performed in a single atomic transaction.
21. A system for writing data in a distributed database having a plurality of nodes, including:
a processor configured to:
receive a write request at a first member node having a first version of a database;
apply the received original write request to both the first version of the database and a journal queue in a single atomic transaction, comprising to:
place the write request in the journal, queue of the first member node, wherein the journal queue is associated with the first member node and is configured to store write requests that have not yet been reconciled with a master version of the database on a master node;
propagate one or more items in the journal queue to the master node;
determine whether a conflict exists between the first version of the database with the write request applied and a master version of the database;
in the event that a conflict exists, reconcile write request with the master version of the database; and
in the event that a conflict does not exist:
determine that the first version of the database is in a high availability pair, wherein the high availability pair includes a second version of the database in a second member node; and
apply the received original write request to both the first version of the database and to the second version of the database in the second member node; and
a memory coupled to the processor and configured to provide the processor with instructions.
22. The system recited in claim 21 , wherein the write request comprises a semantically expressed request to modify the database without sending changed data.
23. The system recited in claim 21 , wherein the write request includes one or more selected from the group consisting of commands, operations and instructions.
24. The system recited in claim 21 , wherein the first member node is an active node and the second member node is a passive node in the high availability pair.
25. The system recited in claim 21 , wherein the second member node is associated with a second journal queue and further including applying the write request to the second version of the database and to the second journal queue in a single atomic transaction.
26. The system recited in claim 21 , wherein the processor is further configured to:
receive from the master node an indication that the one or more items in the journal queue have been reconciled with the master version of the database by the master node.
27. The system recited in claim 21 , wherein the processor is further configured to:
receive from the master node an indication that the one or more items in the journal queue have been reconciled with the master version of the database by the master node; and
in response to receiving the indication, remove the one or more items from the journal queue.
28. The system recited in claim 21 , wherein the processor is further configured to:
receive from the master node an indication that the one or more items in the journal queue have been reconciled with the master version of the database by the master node, wherein the indication indicates whether data in the master version of the database conflicts with the one or more items in the journal queue.
29. The system recited in claim 21 , wherein the processor is further configured to:
receive from the master node an indication that the one or more items in the journal queue have been reconciled with the master version of the database by the master node; and
in the event that the indication indicates a conflict between data in the master version of the database and the one or more items in the journal queue, resolve the conflict.
30. The system recited in claim 21 , wherein the processor is further configured to:
receive from the master node an indication that the one or more items in the journal queue have been reconciled with the master version of the database by the master node; and
in the event that the indication indicates a conflict between data in the master version of the database and the one or more items in the journal queue, resolve the conflict, wherein removing the one or more items from the journal queue and resolving the conflict are performed in a single atomic transaction.