ruby-on-rails - 将外部数据库连接到 Rails 4 App 时出错

Question

我正在尝试将 Postgresql Redshift 数据库添加到我的 Rails 4 应用程序中，以便在本地和生产环境中使用。我首先在开发中进行测试。

我已将我的 database.yml 文件更改为如下所示:

development:
  adapter: postgresql
  encoding: unicode
  database: new_db
  pool: 5
  username: test
  password: password
  host: test_db.us-east-1.redshift.amazonaws.com
  port: 5439

现在，当我点击 localhost:3000 时，我得到了这个错误:

permission denied to set parameter "client_min_messages" to "warning" : SET client_min_messages TO 'warning'

我似乎无法找出造成这种情况的原因 - 似乎我的新数据库不允许 SET 命令？我不太确定，但感谢任何帮助。

Answer 1

刚刚在别处回答了这个问题，但我今天遇到了同样的问题，这就是我所做的并且现在可以正常工作了:

#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，我们连接的是 5439，而不是默认的 5432，所以我指定了端口另外，我指定了一个模式，beta，这是我们用于不稳定聚合的模式，您可以如上所述为每个环境使用不同的数据库，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 

###OPTION 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:

我最终选择了选项 1，但出于多种原因暂时使用此适配器:

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

原因一:ActiveRecord postgresql适配器设置client_min_messages原因 2:适配器还尝试设置 Redshift 不允许的时区(http://docs.aws.amazon.com/redshift/latest/dg/c_redshift-and-postgres-sql.html)原因 3:即使您针对前两个错误更改了 ActiveRecord 中的代码，您也会遇到其他错误，提示 Redshift 使用的是 Postgresql 8.0，此时我转向适配器，如果我发现更好的东西，将重新访问并更新稍后。

我将我的表重命名为 base_aggregate_redshift_tests(注意复数)以便 ActiveRecord 能够轻松连接，如果您不能在 redshift 中更改表名，请使用我在下面注释掉的 set_table 方法

#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

在控制台中使用 self.table_name -- 注意它查询正确的表，因此您可以随意命名您的模型

[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',
    username: 'admin',
    password: 'supersecretpassword',
    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!