Rails 4：将数据库更改为postgresql（来自sqlite3）

Question

所以我想将我的数据库格式sqlite3更改为pg。我尝试了this指南。关于数据库的密码，我不知道我应该在哪里取密码。有默认的吗？

的Gemfile

source 'https://rubygems.org'

gem 'rails', '4.2.5.1'
gem 'pg'
gem 'sass-rails', '~> 5.0'
gem 'uglifier', '>= 1.3.0'
gem 'coffee-rails', '~> 4.1.0'
gem 'decent_exposure'
gem 'slim'
gem 'nprogress-rails'
gem 'jquery-rails'
gem 'turbolinks'
gem 'jbuilder', '~> 2.0'
gem 'sdoc', '~> 0.4.0', group: :doc
gem 'ffaker'

group :development, :test do
  gem 'pry'
end

group :development do
  gem 'pry-rails'
  gem 'better_errors'
  gem 'binding_of_caller'
  gem 'spring'
  # gem 'sqlite3'
end

的database.yml

default: &default
  adapter: postgresql
  host: localhost
  encoding: unicode
  pool: 5

development:
  <<: *default
  database: blog_development

test:
  <<: *default
  database: blog_test

production:
  <<: *default
  database: blog_production

捆绑安装结果100％成功。

当我尝试创建db：

时

bin/rake db:create
Running via Spring preloader in process 12795
could not connect to server: No such file or directory
    Is the server running locally and accepting
    connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:651:in `initialize'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:651:in `new'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:651:in `connect'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:242:in `initialize'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:44:in `new'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:44:in `postgresql_connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:438:in `new_connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:448:in `checkout_new_connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:422:in `acquire_connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:349:in `block in checkout'
/home/dominik/.rvm/rubies/ruby-2.2.4/lib/ruby/2.2.0/monitor.rb:211:in `mon_synchronize'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:348:in `checkout'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:263:in `block in connection'
/home/dominik/.rvm/rubies/ruby-2.2.4/lib/ruby/2.2.0/monitor.rb:211:in `mon_synchronize'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:262:in `connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:571:in `retrieve_connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_handling.rb:113:in `retrieve_connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_handling.rb:87:in `connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/tasks/postgresql_database_tasks.rb:6:in `connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/tasks/postgresql_database_tasks.rb:15:in `create'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/tasks/database_tasks.rb:93:in `create'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/tasks/database_tasks.rb:107:in `block in create_current'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/tasks/database_tasks.rb:275:in `block in each_current_configuration'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/tasks/database_tasks.rb:274:in `each'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/tasks/database_tasks.rb:274:in `each_current_configuration'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/tasks/database_tasks.rb:106:in `create_current'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/railties/databases.rake:17:in `block (2 levels) in <top (required)>'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/task.rb:240:in `call'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/task.rb:240:in `block in execute'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/task.rb:235:in `each'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/task.rb:235:in `execute'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/task.rb:179:in `block in invoke_with_call_chain'
/home/dominik/.rvm/rubies/ruby-2.2.4/lib/ruby/2.2.0/monitor.rb:211:in `mon_synchronize'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/task.rb:172:in `invoke_with_call_chain'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/task.rb:165:in `invoke'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/application.rb:150:in `invoke_task'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/application.rb:106:in `block (2 levels) in top_level'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/application.rb:106:in `each'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/application.rb:106:in `block in top_level'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/application.rb:115:in `run_with_threads'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/application.rb:100:in `top_level'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/application.rb:78:in `block in run'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/application.rb:176:in `standard_exception_handling'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/application.rb:75:in `run'
/home/dominik/github/dd_blog/bin/rake:9:in `<top (required)>'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activesupport-4.2.5.1/lib/active_support/dependencies.rb:268:in `load'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activesupport-4.2.5.1/lib/active_support/dependencies.rb:268:in `block in load'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activesupport-4.2.5.1/lib/active_support/dependencies.rb:240:in `load_dependency'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activesupport-4.2.5.1/lib/active_support/dependencies.rb:268:in `load'
/home/dominik/.rvm/rubies/ruby-2.2.4/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
/home/dominik/.rvm/rubies/ruby-2.2.4/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
-e:1:in `<main>'
Couldn't create database for {"adapter"=>"postgresql", "encoding"=>"unicode", "pool"=>5, "database"=>"blog_development"}

rake db：migrate

rake aborted!
PG::ConnectionBad: could not connect to server: Connection refused
    Is the server running on host "localhost" (127.0.0.1) and accepting
    TCP/IP connections on port 5432?
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:651:in `initialize'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:651:in `new'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:651:in `connect'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:242:in `initialize'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:44:in `new'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:44:in `postgresql_connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:438:in `new_connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:448:in `checkout_new_connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:422:in `acquire_connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:349:in `block in checkout'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:348:in `checkout'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:263:in `block in connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:262:in `connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:571:in `retrieve_connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_handling.rb:113:in `retrieve_connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_handling.rb:87:in `connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/migration.rb:916:in `initialize'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/migration.rb:823:in `new'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/migration.rb:823:in `up'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/migration.rb:801:in `migrate'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/tasks/database_tasks.rb:137:in `migrate'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/railties/databases.rake:44:in `block (2 levels) in <top (required)>'
/home/dominik/.rvm/gems/ruby-2.2.4/bin/ruby_executable_hooks:15:in `eval'
/home/dominik/.rvm/gems/ruby-2.2.4/bin/ruby_executable_hooks:15:in `<main>'
Tasks: TOP => db:migrate
(See full trace by running task with --trace)

请注意，之前我从不使用过postgres。也许需要一些配置？

P.S。我使用的是Ubuntu 14.04

原来，我没有安装postgresql。

Answer 1

有几件事，rake db：migrate只会运行你的迁移，不会创建你的dev deb。创建数据库的命令是：     rake db：create

您只能在创建数据库并连接到数据库后运行迁移。

首先尝试，如果失败，请检查以确保运行postgresql。我在ubuntu 15.04，我运行postgres作为服务看看如果需要的话。确认postgresql已正确安装并正在运行。在终端'psql -V'中将返回已安装的postgresql版本。检查进程$ ps aux | grep postgresl。

确认已启动并运行postgresql后。接下来，从database.yml中删除'host：localhost'行，没有必要。接下来，在database.yml中尝试添加： 您的开发人员数据库下方port: 5432。如果这仍然没有修复它添加： host: ""

Answer 2

1 - 将其添加到您的Gemfile

gem 'pg', '~> 0.15'

2 - 将此添加到您的database.yml，将myapp更改为您的应用程序名称

# PostgreSQL. Versions 8.2 and up are supported.
#
# Install the pg driver:
#   gem install pg
# On OS X with Homebrew:
#   gem install pg -- --with-pg-config=/usr/local/bin/pg_config
# On OS X with MacPorts:
#   gem install pg -- --with-pg-config=/opt/local/lib/postgresql84/bin/pg_config
# On Windows:
#   gem install pg
#       Choose the win32 build.
#       Install PostgreSQL and put its /bin directory on your path.
#
# Configure Using Gemfile
# gem 'pg'
#
default: &default
  adapter: postgresql
  encoding: unicode
  # For details on connection pooling, see rails configuration guide
  # http://guides.rubyonrails.org/configuring.html#database-pooling
  pool: 5

development:
  <<: *default
  database: myapp_development

  # The specified database role being used to connect to postgres.
  # To create additional roles in postgres see `$ createuser --help`.
  # When left blank, postgres will use the default role. This is
  # the same name as the operating system user that initialized the database.
  #username: myapp

  # The password associated with the postgres role (username).
  #password:

  # Connect on a TCP socket. Omitted by default since the client uses a
  # domain socket that doesn't need configuration. Windows does not have
  # domain sockets, so uncomment these lines.
  #host: localhost

  # The TCP port the server listens on. Defaults to 5432.
  # If your server runs on a different port number, change accordingly.
  #port: 5432

  # Schema search path. The server defaults to $user,public
  #schema_search_path: myapp,sharedapp,public

  # Minimum log levels, in increasing order:
  #   debug5, debug4, debug3, debug2, debug1,
  #   log, notice, warning, error, fatal, and panic
  # Defaults to warning.
  #min_messages: notice

# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
test:
  <<: *default
  database: myapp_test

# As with config/secrets.yml, you never want to store sensitive information,
# like your database password, in your source code. If your source code is
# ever seen by anyone, they now have access to your database.
#
# Instead, provide the password as a unix environment variable when you boot
# the app. Read http://guides.rubyonrails.org/configuring.html#configuring-a-database
# for a full rundown on how to provide these environment variables in a
# production deployment.
#
# On Heroku and other platform providers, you may have a full connection URL
# available as an environment variable. For example:
#
#   DATABASE_URL="postgres://myuser:mypass@localhost/somedatabase"
#
# You can use this database configuration with:
#
#   production:
#     url: <%= ENV['DATABASE_URL'] %>
#
production:
  <<: *default
  database: myapp_production
  username: myapp
  password: <%= ENV['MYAPP_DATABASE_PASSWORD'] %>

2 - 然后：

rake db:purge
rake db:setup
rake db:migrate

Answer 3

路轨6 +

在Rails 6.0或更高版本中，您可以运行以下命令：

rails db:system:change --to=postgresql

它还接受mysql，sqlite3，oracle，sqlserver和其他中可见的内容。