The post you're replying to doesn't mention iOS, just mobile (though it may have been edited). Anyway SQLite is heavily used in Android and well, and other mobile platforms going back to all but the early versions of Symbian even. It's been the standard for address book, calendar, settings, to-do apps, etc for over a decade. A typical smartphone probably contains around half a dozen SQLite DBs right out of the box, which means the building I'm in probably houses several thousand of them. The total number of DBs in the world must be in the tens of billions, just from mobile devices.

parent says "Core Data", hence iOS. iOS alone is certainly not the #1 case, since Android has bigger numbers as you know. I just thought it smacked a bit of "Apple bubble", that's all.

Actually, I wouldn't be surprised at all, given that it seems to be the canonical on-disk data store for both Android and iOS. Whether you want to measure total uses by developers, the developers themselves, the users using it, the apps using it, the size data stored, I imagine mobile use probably swamps everything else.

For example, I probably have 20-30 sqlite using apps on my phone, if not more. And I wiped it clean when I got a new phone a few months back and have been fairly hesitant to add apps I haven't found proven use for.