We’re using Trac 0.10.3 in combination with MySQL at work. Trying to setup a new instance and importing the SVN history i faced an ugly duplicate key error trying to insert the revision logs into the database. As this ticket explains this is due to an index over a part of the SVN path affected. By default Trac only uses the first 111 characters of it. This of course will crash if you have deeply nested folders in your project.
As the ticket describes this is just an index and can easily be dropped with
ALTER TABLE `node_change` DROP PRIMARY KEY;