Data replication in active-active databases

A system for managing an active-active database system, the system comprising:

• a processor communicatively coupled to a memory, the processor configured to perform:
• accessing the database system by a processing device, the database system storing a collection of data records, wherein the database system stores a first copy of the data records at a first node, and a second copy of the data records at a second node;
• receiving a first set of operations at the first node, the first set of operations stored at the first node as a first set of local operations, a copy of the first set of operations transmitted to the second node and stored as a first set of remote operations;
• receiving a second set of operations at the second node, the second set of operations stored at the second node as a second set of local operations, a copy of the second set of operations transmitted to the first node and stored as a second set of remote operations;
• determining a comparison point by selecting an operation from each of the first set of operations and the second set of operations;
• comparing the first copy of the data records to the second copy of the data records, wherein the comparing includes:
• comparing values of data records of the first copy that are not changed by operations subsequent to the comparison point, to values of data records of the second copy that are not changed by operations subsequent to the comparison point;
• comparing old data values of data records of the first copy that are updated by one or more subsequent operations, to old data values of data records of the second copy that are updated by one or more subsequent operations;
• comparing operations occurring after the comparison point;
• and
• determining whether the first and second nodes are consistent based on the comparing.

A computer program product for managing an active-active database, comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor to cause the processor to perform a method comprising:

• accessing the database system by a processing device, the database system storing a collection of data records, wherein the database system stores a first copy of the data records at a first node, and a second copy of the data records at a second node;
• receiving a first set of operations at the first node, the first set of operations stored at the first node as a first set of local operations, a copy of the first set of operations transmitted to the second node and stored as a first set of remote operations;
• receiving a second set of operations at the second node, the second set of operations stored at the second node as a second set of local operations, a copy of the second set of operations transmitted to the first node and stored as a second set of remote operations;
• determining a comparison point by selecting an operation from each of the first set of operations and the second set of operations;
• comparing the first copy of the data records to the second copy of the data records, wherein the comparing includes:
• comparing values of data records of the first copy that are not changed by operations subsequent to the comparison point, to values of data records of the second copy that are not changed by operations subsequent to the comparison point;
• comparing old data values of data records of the first copy that are updated by one or more subsequent operations, to old data values of data records of the second copy that are updated by one or more subsequent operations;
• comparing operations occurring after the comparison point;
• and
• determining whether the first and second nodes are consistent based on the comparing.