Old data removed automatically - details?

In the documentation 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.

Start with index.rst and trace the documentation about automatic removal of old data. Confirm how often cleanup runs, which data is removed, and whether configuration exists or a separate cleanup job is needed. Done means the documentation answers these questions clearly, including how to prevent the database from growing too large.

Written by the indexing model from the issue text.