Which database works best with master-master replication?

Question

PostgreSQL

Hello everyone,
the task was to synchronize the database between two servers in master-master mode (that is, each server can write to it). A data update delay of a few seconds is not critical. Correct offline support is important, i.e. database synchronization after a downtime of one of the servers.

First of all, we choose between PostgreSQL and MongoDB. What can be recommended here?

Answer 1

It can be recommended to think three times before using the master-master. The reasons for abandoning the standard type of replication should be directly very weighty, IMHO - to the point that if you need to be able to shut down servers often, reconsider the architecture, placing the DBMS somewhere else, in a less "falling" place.

Answer 2

with master-master replication

Choosing first of all between PostgreSQL and MongoDB

And you specifically choose between DBMS in which there is no multimaster at all?
If you mean any extensions or forks, then call them. One criterion that you need to check you have come up with yourself. The permissible limit on the lag was also named. The second criterion - clearly define your understanding of "correct". At time t the row was updated, at time t+1ms the same row was updated again on another server. There is a replication conflict. What to do? Here is the case for yourself, describe what behavior you want.