AppA stores/retrieves data from dbA.tableA AppB stores/retrieves data from dbB.tableA

tableA definition is the same across these databases. To start with dbB.tableA was copied from dbA.tableA (assuming both had 5 rows).

row6 was created by AppA (say primary key 6) row7 was created by AppB (say primary key 7)

I would like row7 to be copied to dbA.tableA and row6 to dbB.tableA

  1. Is this even possible to setup bi-directional replication, so that the AppA, AppB view the same data at any point in time.
  2. If the primary key is an auto-increment, would it be possible to maintain integrity of data or is there a possibility that there would be collisions on the primary key.
  • Are both dbA and dbB in the same physical server? Apr 6, 2013 at 14:36
  • Can you check if Multi master replication would work? dev.mysql.com/doc/refman/5.1/en/…
    – automatem
    Apr 7, 2013 at 17:47
  • @altmannmarcelo dbA and dbB are in different machines. dbA is in RDS and dbB is a non RDS instance
    – Rpj
    Apr 7, 2013 at 18:31
  • @Rpj Are both MySQL ? Apr 8, 2013 at 8:37

1 Answer 1


I'm assuming these are different instances of MySQL (most likely on different servers).

You can set up Master-master replication, where dbA is a master of dbB and vice versa.

Then, to avoid auto-increment collisions, set the following in my.cnf on dbA:


And the following on dbB:

  • @rpj Please note that the increment config will not solve collisions in the case of a deletes/updates, and it can lead to replication breaking and/or having inconsistent data.
    – jynus
    Jul 6, 2014 at 16:35
  • @jynus Do you mean deletes/updates on primary key only? Jul 10, 2014 at 10:58
  • No, simultaneous deletes and updates on the same rows (no matter the field) will break replication as there is no procedure for conflict resolution/rollbacking. Check these slides (specially page 10 and 11): percona.com/live/mysql-conference-2013/sites/default/files/…
    – jynus
    Jul 10, 2014 at 16:18

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