1 files changed, 66 insertions, 24 deletions
diff --git a/guides/source/active_record_postgresql.md b/guides/source/active_record_postgresql.md
index fe112a4708..68c6a77882 100644
--- a/guides/source/active_record_postgresql.md
+++ b/guides/source/active_record_postgresql.md
@@ -39,7 +39,7 @@ create_table :documents do |t|
 end
 
 # app/models/document.rb
-class Document < ActiveRecord::Base
+class Document < ApplicationRecord
 end
 
 # Usage
@@ -63,7 +63,7 @@ add_index :books, :tags, using: 'gin'
 add_index :books, :ratings, using: 'gin'
 
 # app/models/book.rb
-class Book < ActiveRecord::Base
+class Book < ApplicationRecord
 end
 
 # Usage
@@ -84,8 +84,9 @@ Book.where("array_length(ratings, 1) >= 3")
 ### Hstore
 
 * [type definition](http://www.postgresql.org/docs/current/static/hstore.html)
+* [functions and operators](http://www.postgresql.org/docs/current/static/hstore.html#AEN167712)
 
-NOTE: you need to enable the `hstore` extension to use hstore.
+NOTE: You need to enable the `hstore` extension to use hstore.
 
 ```ruby
 # db/migrate/20131009135255_create_profiles.rb
@@ -97,7 +98,7 @@ ActiveRecord::Schema.define do
 end
 
 # app/models/profile.rb
-class Profile < ActiveRecord::Base
+class Profile < ApplicationRecord
 end
 
 # Usage
@@ -108,6 +109,9 @@ profile.settings # => {"color"=>"blue", "resolution"=>"800x600"}
 
 profile.settings = {"color" => "yellow", "resolution" => "1280x1024"}
 profile.save!
+
+Profile.where("settings->'color' = ?", "yellow")
+#=> #<ActiveRecord::Relation [#<Profile id: 1, settings: {"color"=>"yellow", "resolution"=>"1280x1024"}>]>
 ```
 
 ### JSON
@@ -122,7 +126,7 @@ create_table :events do |t|
 end
 
 # app/models/event.rb
-class Event < ActiveRecord::Base
+class Event < ApplicationRecord
 end
 
 # Usage
@@ -150,7 +154,7 @@ create_table :events do |t|
 end
 
 # app/models/event.rb
-class Event < ActiveRecord::Base
+class Event < ApplicationRecord
 end
 
 # Usage
@@ -200,7 +204,7 @@ create_table :contacts do |t|
 end
 
 # app/models/contact.rb
-class Contact < ActiveRecord::Base
+class Contact < ApplicationRecord
 end
 
 # Usage
@@ -220,15 +224,26 @@ normal text columns:
 
 ```ruby
 # db/migrate/20131220144913_create_articles.rb
-execute <<-SQL
-  CREATE TYPE article_status AS ENUM ('draft', 'published');
-SQL
-create_table :articles do |t|
-  t.column :status, :article_status
+def up
+  execute <<-SQL
+    CREATE TYPE article_status AS ENUM ('draft', 'published');
+  SQL
+  create_table :articles do |t|
+    t.column :status, :article_status
+  end
+end
+
+# NOTE: It's important to drop table before dropping enum.
+def down
+  drop_table :articles
+
+  execute <<-SQL
+    DROP TYPE article_status;
+  SQL
 end
 
 # app/models/article.rb
-class Article < ActiveRecord::Base
+class Article < ApplicationRecord
 end
 
 # Usage
@@ -240,23 +255,50 @@ article.status = "published"
 article.save!
 ```
 
+To add a new value before/after existing one you should use [ALTER TYPE](http://www.postgresql.org/docs/current/static/sql-altertype.html):
+
+```ruby
+# db/migrate/20150720144913_add_new_state_to_articles.rb
+# NOTE: ALTER TYPE ... ADD VALUE cannot be executed inside of a transaction block so here we are using disable_ddl_transaction!
+disable_ddl_transaction!
+
+def up
+  execute <<-SQL
+    ALTER TYPE article_status ADD VALUE IF NOT EXISTS 'archived' AFTER 'published';
+  SQL
+end
+```
+
+NOTE: ENUM values can't be dropped currently. You can read why [here](http://www.postgresql.org/message-id/29F36C7C98AB09499B1A209D48EAA615B7653DBC8A@mail2a.alliedtesting.com).
+
+Hint: to show all the values of the all enums you have, you should call this query in `bin/rails db` or `psql` console:
+
+```sql
+SELECT n.nspname AS enum_schema,
+       t.typname AS enum_name,
+       e.enumlabel AS enum_value
+  FROM pg_type t
+      JOIN pg_enum e ON t.oid = e.enumtypid
+      JOIN pg_catalog.pg_namespace n ON n.oid = t.typnamespace
+```
+
 ### UUID
 
 * [type definition](http://www.postgresql.org/docs/current/static/datatype-uuid.html)
 * [pgcrypto generator function](http://www.postgresql.org/docs/current/static/pgcrypto.html#AEN159361)
 * [uuid-ossp generator functions](http://www.postgresql.org/docs/current/static/uuid-ossp.html)
 
-NOTE: you need to enable the `pgcrypto` (only PostgreSQL >= 9.4) or `uuid-ossp`
+NOTE: You need to enable the `pgcrypto` (only PostgreSQL >= 9.4) or `uuid-ossp`
 extension to use uuid.
 
 ```ruby
 # db/migrate/20131220144913_create_revisions.rb
 create_table :revisions do |t|
-  t.column :identifier, :uuid
+  t.uuid :identifier
 end
 
 # app/models/revision.rb
-class Revision < ActiveRecord::Base
+class Revision < ApplicationRecord
 end
 
 # Usage
@@ -279,12 +321,12 @@ create_table :comments, id: :uuid, default: 'gen_random_uuid()' do |t|
 end
 
 # app/models/post.rb
-class Post < ActiveRecord::Base
+class Post < ApplicationRecord
   has_many :comments
 end
 
 # app/models/comment.rb
-class Comment < ActiveRecord::Base
+class Comment < ApplicationRecord
   belongs_to :post
 end
 ```
@@ -303,7 +345,7 @@ create_table :users, force: true do |t|
 end
 
 # app/models/device.rb
-class User < ActiveRecord::Base
+class User < ApplicationRecord
 end
 
 # Usage
@@ -332,7 +374,7 @@ create_table(:devices, force: true) do |t|
 end
 
 # app/models/device.rb
-class Device < ActiveRecord::Base
+class Device < ApplicationRecord
 end
 
 # Usage
@@ -361,7 +403,7 @@ A point is casted to an array containing `x` and `y` coordinates.
 UUID Primary Keys
 -----------------
 
-NOTE: you need to enable the `pgcrypto` (only PostgreSQL >= 9.4) or `uuid-ossp`
+NOTE: You need to enable the `pgcrypto` (only PostgreSQL >= 9.4) or `uuid-ossp`
 extension to generate random UUIDs.
 
 ```ruby
@@ -372,7 +414,7 @@ create_table :devices, id: :uuid, default: 'gen_random_uuid()' do |t|
 end
 
 # app/models/device.rb
-class Device < ActiveRecord::Base
+class Device < ApplicationRecord
 end
 
 # Usage
@@ -396,7 +438,7 @@ end
 execute "CREATE INDEX documents_idx ON documents USING gin(to_tsvector('english', title || ' ' || body));"
 
 # app/models/document.rb
-class Document < ActiveRecord::Base
+class Document < ApplicationRecord
 end
 
 # Usage
@@ -446,7 +488,7 @@ CREATE VIEW articles AS
   SQL
 
 # app/models/article.rb
-class Article < ActiveRecord::Base
+class Article < ApplicationRecord
   self.primary_key = "id"
   def archive!
     update_attribute :archived, true