Now I understand the problem: When the table is full (DDoS attack or a big number of crawlers), a DB error is thrown and users can't access any page. Which means, that none of the triggers won't be activated.
I've changed the ENGINE type to MyISAM now. So I think this problem will no longer occur!
Thanks a lot,
Daniel
Last edited by DanielH; 10/10/2023 9:42 AM.