I have a web application which currently uses postgres database. But I would like to make my application work in offline too. I found that CouchDB/PouchDB supports offline for web applications. But it says I have to use CouchDB in my existing backend instead of postgres.
I would like to know is it possible to implement CouchDB in web app without changing the existing postgres database?
Do I need to change the postgres database to couchDB to implement this feature?
It is possible to do this - at least in theory. And I have certainly not done any work in this area yet so I cannot advise you on how to implement it. But PouchDb does support LevelUp as a backend to the PouchDb Server (I am not sure if this also applies to the PouchDb client).
This means that you could use PouchDb for your offline web application and sync data to the PouchDb Server, but use the LevelUp capability to use PostGres SQL as the PouchDb Server storage service.
There is a good article by Nolan Lawson entitled "PouchDb levels up" that describes this capability here.
来源：https://stackoverflow.com/questions/46924263/is-it-possible-to-use-two-different-database-for-offline-web-application