You have a rails application with many migrations build over time and you want to recreate the database from start. Should you be using the normal way of running the migrations (db:migrate) or the one that loads the actual schema to the database (db:schema:load).
According to the book Rails 4 in Action (MEAP v9 page 146) :
The bin/rake db:migrate task runs the migrations and then dumps the structure of the database to a file called db/schema.rb. This structure allows you to restore your database using the bin/rake db:schema:load task if you wish, which is better than running all the migrations on a large project again! NOTE
NOTE: Large projects can have hundreds of migrations, which may not run due to changes in the system over time. It’s best to just use the bin/rake db:schema:load.