I had a really great experience building an EAV store with Datalog as the query interface on top of SQLite for embedding in native mobile apps.
Pros: querying complex data hierarchies was easy, and was able to skip the pain typically associated with managing a SQL schema.
I would love to hear more! Did you write the datalog layer or is there one somewhere? Is there any code available I could see?
You might be interested in the now defunct Mentat project from Mozilla. They made an EAV store with syncing on top of sqlite. It ran datalog queries by translating them into sql.