How to identify the type of database file from a data dump?

I have a file that I suspect is a database, but I don't know what kind of database it is (SQLite, Postgres, etc.). How can I infer test if it's a database, and if so, what kind of database it is? If it's a database, it's using a public database system. I tried reading the file with an hex editor but didn't see any obvious hint in it (at least, nothing obvious to me).