The changes to the database schema must be done in the xml files from the lib/srdb1/schema/. The sql or other db definition files are auto-generated from xml files using **make dbschema**.
Also, it may be good that there will be a discussion on sr-users mailing list to see what would be a good size to increase to, not to jump to 64 and then see other people would like 128 or other max length.