Merge two large MySQL databases whilst maintaining referential integrity

Question

I have two large (6GB and 8GB respectively) MySQL databases which have identical schemas, and a common history up until about 6 weeks ago.

They differ from that point, and therefore, after that point, will have conflicting primary keys.

I want to merge these two databases - whilst maintaining referential integrity.

Initially, I tried to diff the databases using git, however git falls over when trying to resolve deltas on BLOBs within the databases.

Can anyone suggest a way of doing this?

Edit : Although it would have been a good idea at the time, I don't have any binary logs for either database

Answer 1

I think a good idea is make a script to migrate data and then iterate over the small database and add the records to the bigger database.

Make tests in a development environment and after confirm that it works, run in production.