I have never seen a company moving to another database. This is something that just does not happen.
I hope you're being sarcastic.
In case you aren't:
Why Uber Engineering Switched from Postgres to MySQL
Why we Moved From NoSQL MongoDB to PostgreSQL
From my mobile experience there is Parse who burned its developers 2 years ago. My personal app is still not working because i could not replicate in Firebase the query based on location coordinates. Since then i learned to use clean code and the database is switchable whenever i wish. I do have one right now where an iOS, Mac and command line app use the same codebase but different databases.
Of course, if you have something highly important no need to worry about this and better to implement how is more efficient.
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