Does Drupal have a system for noticing and logging changes to records?
There is the Track Field Changes module which appears to have little support. And also a -dev version of Node Changes module with many more contributors and more recent updates.

Both modules allow you to track field level changes on Nodes essentially. From Node Changes:


  This module stores the changes of a node into a field attached to
  comments allowing to display a kind-of activity stream on the node
  much like on drupal.org issues just with a lot less custom code.


I don't believe either makes use of database triggers.