Put simply - SQLite is incredibly powerful and simple - it can handle a lot more then people might think - and AFAIK it is the most "used in production" database whether you're aware of it or not.
Depending on the use case it can scale incredibly well, and is tiny and battle hardened.
It's the most deployed database, it's on every smartphone, "smart device", computer, it's inside of many of your apps, powers many of the websites you use, etc.
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tl;dr - If you're following "use the simplest, but reliable tool for the job" then sqlite is a valid option for a crapload of use cases, most people aren't aware of what it can actually do because it doesn't "web scale".
Sqlite isn't new, it's old, and it's "used in production" count is in the literal billions.
Depending on the use case it can scale incredibly well, and is tiny and battle hardened.
It's the most deployed database, it's on every smartphone, "smart device", computer, it's inside of many of your apps, powers many of the websites you use, etc.
---
tl;dr - If you're following "use the simplest, but reliable tool for the job" then sqlite is a valid option for a crapload of use cases, most people aren't aware of what it can actually do because it doesn't "web scale".
Sqlite isn't new, it's old, and it's "used in production" count is in the literal billions.