#app/models/data_warehouse.rb
class DataWarehouse < ActiveRecord::Base                      
  establish_connection "redshift_staging"
  #or,if you want to have a db per environment
  #establish_connection "redshift_#{Rails.env}"
end

请注意,我们正在连接5439,而不是默认的5432,所以我指定端口
此外,我指定了一个模式,beta,这是我们用于不稳定聚合的模式,如上所述,您可以为每个环境创建不同的数据库,或者使用各种模式,并将它们包含在ActiveRecord的搜索路径中

#config/database.yml
redshift_staging:                                                          
  adapter: postgresql                                                      
  encoding: utf8                                                           
  database: db03                                                         
  port: 5439                                                               
  pool: 5                                                                  
  schema_search_path: 'beta'                                                                                          
  username: admin                                                        
  password: supersecretpassword                                               
  host: db03.myremotehost.us  #your remote host here,might be an aws url from Redshift admin console

###选项2,直接PG连接

class DataWarehouse < ActiveRecord::Base                      

    attr_accessor :conn                                                       

    def initialize                                                            
      @conn = PG.connect(                                                     
       database: 'db03',port: 5439,pool: 5,schema_search_path: 'beta',username: 'admin',password: 'supersecretpassword',host: 'db03.myremotehost.us'                                               
      )                                                                       
    end    
  end


[DEV] main:0> redshift = DataWarehouse
E,[2014-07-17T11:09:17.758957 #44535] ERROR -- : PG::InsufficientPrivilege: ERROR:  permission denied to set parameter "client_min_messages" to "notice" : SET client_min_messages TO 'notice'
(pry) output error: #<ActiveRecord::StatementInvalid: PG::InsufficientPrivilege: ERROR:  permission denied to set parameter "client_min_messages" to "notice" : SET client_min_messages TO 'notice'>

更新：

我结束了选项1,但现在使用这个适配器有多个原因：

https://github.com/fiksu/activerecord-redshift-adapter

原因1：ActiveRecord postgresql适配器设置client_min_messages
原因2：适配器也尝试设置时区,红移不允许(http://docs.aws.amazon.com/redshift/latest/dg/c_redshift-and-postgres-sql.html)
原因3：即使您在前两个错误中更改了ActiveRecord中的代码,您也遇到了其他错误,这些错误提示Redshift正在使用Postgresql 8.0,那时我转到适配器,如果我找到更好的东西,将会重新访问和更新后来.

我将我的表重命名为base_aggregate_redshift_tests(注意复数),所以ActiveRecord很容易连接,如果你不能更改你的表名在redshift使用set_table方法我已经注释掉下面

#Gemfile:
gem 'activerecord4-redshift-adapter',github: 'aamine/activerecord4-redshift-adapter'

选项1

#config/database.yml
redshift_staging:                                                                                                             
  adapter: redshift                                                                                                           
  encoding: utf8                                                                                                              
  database: db03                                                                                                           
  port: 5439                                                                                                                  
  pool: 5                                                                                                                     
  username: admin                                                                                                
  password: supersecretpassword                                                                                                  
  host: db03.myremotehost.us                                                                                                       
  timeout: 5000   

#app/models/base_aggregates_redshift_test.rb
#Model named to match my tables in Redshift,if you want you can set_table like I have commented out below

class BaseAggregatesRedshiftTest < ActiveRecord::Base
  establish_connection "redshift_staging"
  self.table_name = "beta.base_aggregates_v2"
end

在控制台使用self.table_name – 通知它查询正确的表,所以你可以命名你的模型,无论你想要什么

[DEV] main:0> redshift = BaseAggregatesRedshiftTest.first                                                                    
D,[2014-07-17T15:31:58.678103 #43776] DEBUG -- :   BaseAggregatesRedshiftTest Load (45.6ms)  SELECT "beta"."base_aggregates_v2".* FROM "beta"."base_aggregates_v2" LIMIT 1

选项2

#app/models/base_aggregates_redshift_test.rb
class BaseAggregatesRedshiftTest < ActiveRecord::Base
  set_table "beta.base_aggregates_v2"

  ActiveRecord::Base.establish_connection(
    adapter: 'redshift',encoding: 'utf8',database: 'staging',port: '5439',pool: '5',search_schema: 'beta',host: 'db03.myremotehost.us',timeout: '5000'
  )

end

#in console,abbreviated example of first record,now it's using the new name for my redshift table,just assuming I've got the record at base_aggregates_redshift_tests because I didn't set the table_name

[DEV] main:0> redshift = BaseAggregatesRedshiftTest.first
D,[2014-07-17T15:09:39.388918 #11537] DEBUG -- :   BaseAggregatesRedshiftTest Load (45.3ms)  SELECT "base_aggregates_redshift_tests".* FROM "base_aggregates_redshift_tests" LIMIT 1
#<BaseAggregatesRedshiftTest:0x007fd8c4a12580> {
                                                :truncated_month => Thu,31 Jan 2013 19:00:00 EST -05:00,:dma => "Cityville",:group_id => 9712338,:dma_id => 9999 
                                                }

祝你好运@johncorser！