Can I delete entries from qa_blobs when I am sure that those images are not used in any question or post?
Actually I did so, but clicking on "filename" now (to sort the entries) returns:
MySQL returned an empty result set (i.e. zero rows).
The mysql for sorting is:
ORDER BY `qa_blobs`.`filename` ASC
LIMIT 300 , 30
// 300 ? strange
Update: Now sorting works, I logged out, and cleared the cache of my browser.