Subject Sticky replication issue
Author Joe Martinez
I'm planning to add n-way replication abilities to my application. My
question is about conflict resolution, where two different locations modify
the same record.

I was reading IBReplicator's description of this type of conflict
resolution, saying that you can have it Priority-Based (you set the
different locations' priorities, and whichever one has the higher priority
"wins"), timestamp-based (either the earliest or the latest timestamp
"wins"). The other option is master-slave, which isn't n-way replication.

Here's the issue: Our CUSTOMERS table has a field that tracks "points"
earned by a customer for their purchases (a customer incentive
program). This is a single field in the CUSTOMERS table, that's simply a
running total. Let's say at the start of the day, a customer has 25
points, which is reflected correctly at all locations. The customer earns
5 points at location A. It's database now shows that the customer has 30
points (25+5=30). The customer then drives across town to location B and
earns 10 points, so it's database now shows 35 points (25+10=35). Now,
it's the end of the day, and it's time to do the replication. What we
REALLY want is for both databases to show 40 points (25+5+10=40). I don't
see how either priority-based or timestamp-based conflict resolution could
possibly make this happen, because the number 40 was never written to
EITHER database.

How could this be accomplished?