转储postgres DB导轨

Question

There is a lot of info about how to dump a database so it can be moved into production, but none of it seems to mention what the username of the database should be.

This is from Heroku, but I can't find the username...

PGPASSWORD=mypassword pg_dump -Fc --no-acl --no-owner -h localhost -U myuser mydb mydb.dump

This is from a rake task I found on Github

 desc "Dumps the database to db/APP_NAME.dump"
  task :dump => :environment do
    cmd = nil
    with_config do |app, host, db, user|
      cmd = "pg_dump --host #{host} --username #{user} --verbose --clean --no-owner --no-acl --format=c #{db} > #{Rails.root}/db/#{app}.dump"
    end
    puts cmd
    exec cmd
  end

  def with_config
    yield Rails.application.class.parent_name.underscore,
      ActiveRecord::Base.connection_config[:host],
      ActiveRecord::Base.connection_config[:database],
      ActiveRecord::Base.connection_config[:username]
  end

It generates the following command with the following error.

pg_dump --host --username --verbose --clean --no-owner --no-acl --format=c kelp_development > /home/yiti/code/ymagoon/kelp/db/kelp.dump

pg_dump: [archiver (db)] connection to database "kelp_development" failed: could not translate host name "--username" to address: Name or service not known

Answer 1

You can find the details about your postgres database on the Heroku Dashboard:

1. Open Heroku Dashboard
2. Select your application
3. On the tab 'Overview', click on 'Heroku Postgres', a new browserwindow opens.
4. In the new browserwindow, select the tab 'Settings'
5. Click on 'View credentials...'
6. Your DB settings are all listed here

Don't forget the warning on this page: Please note that these credentials are not permanent.

Answer 2

As per the description and code shared it seems like you have not specified the host , database and username.

Below mentioned command shows that it is not picking up the configuration from the with_config method defined in the rake task.

pg_dump --host  --username  --verbose --clean --no-owner --no-acl --format=c kelp_development > /home/yiti/code/ymagoon/kelp/db/kelp.dump

You can create a configuration object with the below mentioned code

config   = Rails::Configuration.new
host     = config.database_configuration[RAILS_ENV]["host"]
database = config.database_configuration[RAILS_ENV]["database"]

Get the database credentials from DATABASE_URL scheme://username:password@host:port/database

Now you can directly dump the data to postgres database from the below mentioned commmad:

pg_dump -h host_name -U user_name --verbose --clean --no-owner --no-acl --format=c db_name > path_to_dump_file.dump