Nepomuk and MySQL - Why?

[Mark]

Hi,

Every time when i start a brand new KDE session with a new user i see
some stuff passing by with MySQL.. Now i understand a database is
needed for nepomuk but does it have to be a heavy weight one like
MySQL?

MySQL is not only big in hdd footprint, it also loves to suck up
memory. Some alternatives i can think of:
- SQLite
- MongoDB

A bit about MongoDB. That "database" spits data out in BSON format
(Binary JSON) which -to me- seems to perfectly fit the the QML
strategy that KDE seems to be going to (for KDE 5.0 or so?). It
prevents conversion to JSON and thus would seem like a perfect fit for
QML plasmoids. On the C++ side things are a bit different. There is a
C++ wrapper for MongoDB but it uses boost. There is no native Qt
wrapper for MongoDB (yet).

The advantages of using MongoDB over MySQL are (that i can think of in
a few seconds):
- Just a few MB hdd footprint for the binary and libs
- Faster then MySQL
- Easy to use in QML plasmoids

The disadvantage is obviously more hdd space for the "database" itself
and no existing Qt wrapper.

So, why is MySQL used and not a lighter alternative like SQLite or MongoDB?

Please do note that this is by no means a intent to start a flame war
or anything! I'm just curious behind the MySQL reasoning and if it's
worth a consideration to move to another lighter database.

Kind regards,
Mark