The details or status of this tracker issue were updated by PDStig

Composr does not officially support flat-file installs. There is the XML driver, but it is only available when using Composr from Git (it was intended for development testing only and has a lot of nuances).

In fact, the XML driver does not work at all in v11, and I have no plans right now to fix it (costs outweigh benefits).

However, I'd suggest adding a feature request for something like SQLite support, which can easily be done since PHP supports it natively.

I'm adding SQLite 3 to v11 beta9. But it will only have basic support. It won't work well for major upgrades at this time because it doesn't support changing column properties (without creating a new table and migrating everything over).

I'm mainly doing this for additional dev testing capabilities. But it will work for admins of simple sites who want just a flat file for the database.

Cool, not sure how useful it will be for my use case. It seems the galleries table takes up a lot of my database and that keeps on growing, hence why I tried the option in v10. Sadly, v10 did not deliver.