Hello, I'm a little embarrassed for this question, but couldn't find a solution on my own.
All of my photo collections lives in ~/pictures/digikam/[my_albums], only database files live in ~/pictures, which is not so handy. How can I (easily) change the location of database files to ~/pictures/digikam/ ?

Cheers,
Wolf

Embarrassing indeed.
Just go to Settings > Configure Digikam > Database.
Choose a new location - and the programme will move your existing database there. No hassle at all.

Cheers,
Wolf