This command is used to load a large data set into table.
The basic usage COPY country FROM '/usr1/proj/bray/sql/country_data';
is work only for existing file on postgres server, which might caught problem with heroku web app.
To do that with django project, you can use the method cursor.copy_from
https://pythonhosted.org/psycopg2/cursor.html#cursor.copy_from
With RoR, this may help http://stackoverflow.com/questions/14526489/using-copy-from-in-a-rails-app-on-heroku-with-the-postgresql-backend
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