Update 8 changes how the database log is logging changes to data. Before Update 8 this was handled through triggers in the kernel and then some application code.
In Update 8 this now happens on triggers created on the SQL Database for each table you enable logging on.
You can still find the old application code in Update 8, but it is not triggered anymore.
There is a bit more information on this community thread: https://community.dynamics.com/ax/f/33/p/246718/684546#684546
