How are the real time subscriptions with SQLite achieved? Is this a feature of SQLite itself or something that PocketBase itself implements on top of it?
The realtime api implementation could be found at https://github.com/pocketbase/pocketbase/blob/master/apis/re...
This looks like a very interesting project and great for some of the small client projects which I currently use Firebase. I'll be sure to take a proper look in the future!
User defined filters for the subscriptions are not supported, but it's a good idea and I may consider it in the future.
Currently the subscriptions are filtered through the collection's list and view rules - they also act as "admin level filters", aka. filters that are always applied and regular users cannot modify (getList user defined filters are only appended to the search query together with the admin defined filters).