heroku 上运行 rake db:migrate 上的重复表错误，解决此问题的下一步是什么

Question

终端上的命令： $ heroku run rake db:migrate

终端上的错误：

PG::DuplicateTable: ERROR:  relation "users" already exists
: CREATE TABLE "users" ("id" serial primary key, "email" character varying(255) DEFAULT '' NOT NULL, "encrypted_password" character varying(255) DEFAULT '' NOT NULL, "reset_password_token" character varying(255), "reset_password_sent_at" timestamp, "remember_created_at" timestamp, "sign_in_count" integer DEFAULT 0, "current_sign_in_at" timestamp, "last_sign_in_at" timestamp, "current_sign_in_ip" character varying(255), "last_sign_in_ip" character varying(255)) /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.2/lib/active_record/connection_adapters/postgresql/database_statements.rb:128:in `async_exec'

在db/migrate 文件夹下有 2 个文件，如下所示：

20140503215545_devise_create_users.rb

class DeviseCreateUsers < ActiveRecord::Migration
  def change
    create_table(:users) do |t|
      ## Database authenticatable
      t.string :email,              :null => false, :default => ""
      t.string :encrypted_password, :null => false, :default => ""
      ## Recoverable
      t.string   :reset_password_token
      t.datetime :reset_password_sent_at
      ## Rememberable
      t.datetime :remember_created_at
      ## Trackable
      t.integer  :sign_in_count, :default => 0
      t.datetime :current_sign_in_at
      t.datetime :last_sign_in_at
      t.string   :current_sign_in_ip
      t.string   :last_sign_in_ip
      t.timestamps
    end
    add_index :users, :email,                :unique => true
    add_index :users, :reset_password_token, :unique => true
  end
end

20140503215546_add_devise_to_users.rb

class AddDeviseToUsers < ActiveRecord::Migration
  def self.up
    create_table(:users) do |t|
      ## Database authenticatable
      t.string :email,              :null => false, :default => ""
      t.string :encrypted_password, :null => false, :default => ""
      ## Recoverable
      t.string   :reset_password_token
      t.datetime :reset_password_sent_at
      ## Rememberable
      t.datetime :remember_created_at
      ## Trackable
      t.integer  :sign_in_count, :default => 0
      t.datetime :current_sign_in_at
      t.datetime :last_sign_in_at
      t.string   :current_sign_in_ip
      t.string   :last_sign_in_ip
      # Uncomment below if timestamps were not included in your original model.
      # t.timestamps
    end
    add_index :users, :email,                :unique => true
    add_index :users, :reset_password_token, :unique => true
    # add_index :users, :confirmation_token,   :unique => true
    # add_index :users, :unlock_token,         :unique => true
    # add_index :users, :authentication_token, :unique => true
  end
  def self.down
    # By default, we don't want to make any assumption about how to roll back a migration when your
    # model already existed. Please edit below which fields you would like to remove in this migration.
    raise ActiveRecord::IrreversibleMigration
  end
end

我对轨道很陌生。建议我成功运行此迁移的方法。

Answer 1

它们实际上是重复的。第二次迁移在较旧的迁移 API 中（使用 self.up 和 self.down），第一次迁移使用较新的迁移 API（只是change实例方法）。

我会删除第二次迁移，在本地迁移，然后推送到 heroku 并重试。