db:drop, pg_restore
do in this order:
delete from migration_schema rake db:drop rake db:create rake db:migrate pg_restore --verbose -a --no-acl --no-owner -h localhost -d libval_development ~/Desktop/20150311.dump
UPDATE: only using pg_restore obviously doesn't work on existing db; if you don't care about existing data:
sudo -u postgres pg_restore --create --clean -d postgres /path/to/dbbackup.sql
doesnt work on mbp
http://dba.stackexchange.com/a/66705






