How to point to correct data in a database

Question

There are 2 Oracle databases with the same tables on two different servers. Database A on server A and Database B on server B

A: Table1,Table2

B: Table1,Table2

These tables are identical to each other, in that it's possible to copy the data tables from server A to server B. We only have remote access to the database on Server A, but full admin access to Server B.

So, database A is remote and has a primary and secondary DB. The secondary DB gets updated with the latest data, then we must switch the DB we're pointing to towards secondary. Same for the opposite, when things are pointing to secondary, primary DB will get updated with data, then the system should point to Database A primary. This way the database is never down we just switch what we point to after the other one gets updated.

There is also a web interface that sets a config file whether we're pointing to the primary or the secondary DB

Now, I'm trying to come up with solutions on how to get/synchronize/copy/point to the correct database to get the updated data either directly from A or by copying data A to B.

Solution 1) We read db config file and point directly to the primary (or secondary) DB

Solution 2) Build a windows service that will detect when primary or secondary DB gets updated, and copy tables from DataBase A to DataBase B.

Solution 3) Have a "copy tables" button on the web interface that will start a background task of copying data from A to B using http://hangfire.io

Solution 4) ??

So far, I like the idea of solution 1 the best, where we just point directly to either the primary or secondary DB based on configuration. This idea doesn't involve any copying to the identical tables on Server B.

However, I was wondering if there is any other possible solution? Would triggers, replication, or something else work here?

Thanks.