Old data removed automatically - details?

[mortenholmgaard]

In index.rst it states that old data is removed automatically:
"Server is also responsible to keep the storage clean and remove old data automatically."
How often and which data is removed? Are there any ways to change configuration of that or do you have to write a cleanup job your self?
E.g. to make sure that database does not fill to much.

[mortenholmgaard]

Any one?