rake db：最近遷移的回滾掛起

Question

我有一個rails應用程序，我最初在rails 3中編寫，並在一個月前升級到rails 3.1.10。我只是在故事和標籤之間創建了一個habtm關聯，以及相關的數據庫遷移。

class Story < ActiveRecord::Base 

    belongs_to :user 
    has_and_belongs_to_many :tags, :uniq => true 

end 

---

class Tag < ActiveRecord::Base 

    has_and_belongs_to_many :stories, :uniq => true 

end 

---

class CreateTags < ActiveRecord::Migration 
    def change 
    create_table :tags do |t| 
     t.string :name 

     t.timestamps 
    end 
    end 
end 

---

class CreateStoriesTags < ActiveRecord::Migration 
    def change 
    create_table :stories_tags, :id => false do |t| 
     t.references :story, :tag 
    end 

    add_index :stories_tags, [:story_id, :tag_id] 
    end 
end 

最後，這裏是有關schema.db：

create_table "stories", :force => true do |t| 
    t.string "title" 
    t.integer "user_id" 
    t.datetime "created_at" 
    t.datetime "updated_at" 
    end 

    add_index "stories", ["user_id"], :name => "index_stories_on_user_id" 

    create_table "stories_tags", :id => false, :force => true do |t| 
    t.integer "story_id" 
    t.integer "tag_id" 
    end 

    add_index "stories_tags", ["story_id", "tag_id"], :name => "index_stories_tags_on_story_id_and_tag_id" 

    create_table "tags", :force => true do |t| 
    t.string "name" 
    t.datetime "created_at" 
    t.datetime "updated_at" 
    end 

我遷移了數據庫，然後在控制檯中關聯了這些關聯。現在我想要回滾遷移，以便爲標記表添加一些額外的列。 （我知道我可以簡單地創建一個新的遷移，但我還是想知道爲什麼我現在面臨這個問題）。現在，當我插入rake db:rollback到控制檯這裏是初始輸出：

[nw0.0.1master (development)]$ rake db:rollback 
== CreateStoriesTags: reverting ============================================== 
-- drop_table(:stories_tags) 

到目前爲止這麼好，但隨後耙子任務就掛起了。 。 。用了幾個小時。如果我CTRL-C出它這裏是輸出到控制檯：

^Crake aborted! 
An error has occurred, this and all later migrations canceled: 

Interrupt: : ROLLBACK 
/.rvm/gems/ruby-1.9.2-p290@rails3firstgemset/gems/activerecord-3.1.10/lib/active_record/connection_adapters/postgresql_adapter.rb:605:in `async_exec' 
/.rvm/gems/ruby-1.9.2-p290@rails3firstgemset/gems/activerecord-3.1.10/lib/active_record/connection_adapters/postgresql_adapter.rb:605:in `block in execute' 
/.rvm/gems/ruby-1.9.2-p290@rails3firstgemset/gems/activerecord-3.1.10/lib/active_record/connection_adapters/abstract_adapter.rb:245:in `block in log' 
/.rvm/gems/ruby-1.9.2-p290@rails3firstgemset/gems/activesupport-3.1.10/lib/active_support/notifications/instrumenter.rb:21:in `instrument' 
/.rvm/gems/ruby-1.9.2-p290@rails3firstgemset/gems/activerecord-3.1.10/lib/active_record/connection_adapters/abstract_adapter.rb:240:in `log' 
/.rvm/gems/ruby-1.9.2-p290@rails3firstgemset/gems/activerecord-3.1.10/lib/active_record/connection_adapters/postgresql_adapter.rb:604:in `execute' 
/.rvm/gems/ruby-1.9.2-p290@rails3firstgemset/gems/activerecord-3.1.10/lib/active_record/connection_adapters/postgresql_adapter.rb:664:in `rollback_db_transaction' 
/.rvm/gems/ruby-1.9.2-p290@rails3firstgemset/gems/activerecord-3.1.10/lib/active_record/connection_adapters/abstract/database_statements.rb:201:in `rescue in transaction' 
/.rvm/gems/ruby-1.9.2-p290@rails3firstgemset/gems/activerecord-3.1.10/lib/active_record/connection_adapters/abstract/database_statements.rb:182:in `transaction' 
/.rvm/gems/ruby-1.9.2-p290@rails3firstgemset/gems/activerecord-3.1.10/lib/active_record/transactions.rb:208:in `transaction' 
/.rvm/gems/ruby-1.9.2-p290@rails3firstgemset/gems/activerecord-3.1.10/lib/active_record/migration.rb:742:in `ddl_transaction' 
/.rvm/gems/ruby-1.9.2-p290@rails3firstgemset/gems/activerecord-3.1.10/lib/active_record/migration.rb:686:in `block in migrate' 
/.rvm/gems/ruby-1.9.2-p290@rails3firstgemset/gems/activerecord-3.1.10/lib/active_record/migration.rb:671:in `each' 
/.rvm/gems/ruby-1.9.2-p290@rails3firstgemset/gems/activerecord-3.1.10/lib/active_record/migration.rb:671:in `migrate' 
/.rvm/gems/ruby-1.9.2-p290@rails3firstgemset/gems/activerecord-3.1.10/lib/active_record/migration.rb:553:in `down' 
/.rvm/gems/ruby-1.9.2-p290@rails3firstgemset/gems/activerecord-3.1.10/lib/active_record/migration.rb:627:in `move' 
/.rvm/gems/ruby-1.9.2-p290@rails3firstgemset/gems/activerecord-3.1.10/lib/active_record/migration.rb:541:in `rollback' 
/.rvm/gems/ruby-1.9.2-p290@rails3firstgemset/gems/activerecord-3.1.10/lib/active_record/railties/databases.rake:232:in `block (2 levels) in <top (required)>' 
Tasks: TOP => db:rollback 
(See full trace by running task with --trace) 

幾件事情要注意，因爲這個程序開始了W /導軌3.0，所有早期的遷移使用舊Class.up Class.down方法來定義遷移。另外，當我第一次查看懸掛時，我​​將CreateStoriesTags遷移切換爲使用up和down實例方法，但一切仍然懸掛。

UPDATE AND THE ANSWER

我注意到PGAdmin3 Workbench也掛了。所以，我重新啓動了Mac，現在回滾正在發現。

Answer 1

原來我的db服務器有問題。一個簡單的重新啓動就解決了這個問題