Ah, with MySQL you're making a distinction between the MySQL package and the data storage mechanism, which is part of the (R)DBMS. InnoDB is basically a table format specification that got its start with MySQL, but got forked together with MariaDB.I'm not much of a DB guy but it could be to do with storage engines?
For example MySQL is the DBMS, whereas InnoDB is an example of the DB.
Likewise Oracle's BerkelyDB is the DB whereas SQLite3 can be used as its "DBMS" (more of a frontend API) since 11g R2.
This may be heresy to say to an actual DBA but I feel that for 99% of use-cases these days, on such powerful machines, SQLite is probably enough
I.e back in the day, running a forums on an embedded DB would not be ideal but now it is possibly quite feasible? Or I am just exposing my lack of knowledge here XD
BDB is another table format spec (I thought that one was from BSD, rather than Oracle). SQLite3 is basically a C API to flat-file DB2 table format that was developed by IBM (IIRC). BTW, storage engines are not the same thing as storage formats. A storage format can be expressed as an XML file, while a storage engine is not amenable to such expression.