SymmetricDS - conflict resolution

Question

I am trying to implement multi-master bidirectional synchronization for one central node and many clients using SymmetricDS. Clients are communicating only with central node (star topology). I have problem with dealing with conflicts in primary keys.

For example database contains table "person" with columns id, name,... In central db I have rows:

1. aaa
2. bbb
3. ccc

First client connects and downloads initial load, so it has same db. Second client do the same.

Now first and second clients create new row in their local db. First:

1. aaa
2. bbb
3. ccc
4. ddd

Second:

1. aaa
2. bbb
3. ccc
4. eee

They will try sync, but there is conflict in 4. row. This conflict can be easily detected in SymmetricDS, but now I want to resolve it by increment key until it's inserted and then send changes back to the clients... So result will be:

1. aaa
2. bbb
3. ccc
4. ddd
5. eee

in every database. How can it be done? Thank you.

Answer 1

When dealing with a multi-master bi-directional scenario its not a good idea to use an auto incrementing PK.

Standard practice is to create a GUID for the PK to avoid conflicts between your clients.

See the following site for more details.

Selecting an Appropriate Primary Key for a Distributed Environment