Take a look at the link below, scroll down to the headline “Situations Where A Client/Server RDBMS May Work Better”.

https://sqlite.org/whentouse.html

At "Ask HN: Do you self-host your database?"

https://news.ycombinator.com/item?id=27671376

is this comment:

https://news.ycombinator.com/item?id=27673359

"We're currently transitioning from a multi-tenant 2TB postgres DB hosted on AWS RDS to using sqlite instead, a separate database for each client.

We're doing this for multiple reasons:

a) As our DB grew the service became very expensive, one of the biggest items in our AWS invoice;

b) Keeping the PG servers up to date is a pain, we simply don't have time for this;

c) We wanted to be able to migrate to other clouds and even be able to offer a self-hosted version of our platform."

SQLite was created, because client-server database Informix (similar to MySQL and PosgreSQL) did crash and and was unavailable to connect to. There are some edge cases where MySQL/PostgreSQL can start vacuum, be corrupted, etc making client/server database unavailable. SQLite is tested with billions of test cases.

In interview:

"The idea for SQLite actually came out of his frustrations with an existing database called Informix that was installed on a literal battleship."

"Why do we even need a server? Why can’t I pull this directly off the disk drive? That way if the computer is healthy enough, it can run our application at all, we don’t have dependencies that can fail and cause us to fail, and I looked around and there were no SQL database engines that would do that, and one of the guys I was working with says, “Richard, why don’t you just write one?” “Okay, I’ll give it a try.” "

access management, and scalability: can better do simultaneous writes, and use several copies horizontally

BUT: you probably need 1k+ or 10k+ requests per second to start getting advantages