在日志中包含 Active Record 查询的作用

Question

Rails 现在支持多个数据库角色（默认情况下，writing对于主数据库和reading副本数据库角色）：

ActiveRecord::Base.connected_to(role: :reading) do
  # all code in this block will be connected to the reading role
end

在开发中，默认情况下会记录 Active Record 查询，例如：

> User.last
  User Load (0.1ms)  SELECT "users".* FROM "users" ORDER BY "users"."id" DESC LIMIT ?  [["LIMIT", 1]]

如何在日志记录中包含用于查询的角色？例如：

> ActiveRecord::Base.connnected_to(role: :reading) { User.last }
  [role: reading] User Load (0.1ms)  SELECT "users".* FROM "users" ORDER BY "users"."id" DESC LIMIT ?  [["LIMIT", 1]]

Answer 1

因为所有查询都将在最后一步由AbstractAdapter 类的方法日志记录，无论您使用哪种数据库适配器：postgresql，mysql，..因此您可以覆盖该方法并在前面添加role

# lib/extent_dblog.rb
ActiveRecord::ConnectionAdapters::AbstractAdapter.class_eval do
  alias_method(:origin_log, :log)
  def log(sql, name = 'SQL', binds = [], 
          type_casted_binds = [], statement_name = nil, &block)
    # prepend the current role before the log
    name = "[role: #{ActiveRecord::Base.current_role}] #{name}"
    origin_log(sql, name, binds, type_casted_binds, statement_name, &block)
  end
end

# config/initializers/ext_log.rb
require File.join(Rails.root, "lib", "extent_dblog.rb")

演示

# config/application.rb
  ...
  config.active_record.reading_role = :dev
  config.active_record.reading_role = :test

# app/models/application_record.rb
 class ApplicationRecord < ActiveRecord::Base
   self.abstract_class = true
   connects_to database: { dev: :development, test: :test }
 end

ActiveRecord::Base.connected_to(role: :dev) do
  Target.all
end
# [role: dev]  (0.6ms)  SELECT "targets".* FROM "targets" 

Answer 2

config/initializers/multidb_logger.rb使用以下代码创建一个新文件 ：

ActiveRecord::ConnectionAdapters::AbstractAdapter.class_eval do
  alias_method(:origin_log, :log)
  def log(sql, name = 'SQL', binds = [], type_casted_binds = [], statement_name = nil, &block)
    sql = "#{sql} /* #{@config[:replica] ? 'REPLICA' : 'MASTER'} DB */"
    origin_log(sql, name, binds, type_casted_binds, statement_name, &block)
  end
end

ActiveRecord::LogSubscriber.class_eval do
  alias_method(:origin_extract_query_source_location, :extract_query_source_location)
  def extract_query_source_location(locations)
    new_locations = locations.reject { |loc| loc.include? File.basename(__FILE__) }
    origin_extract_query_source_location(new_locations)
  end
end

现在，在 ActiveRecord 记录的 SQL 查询中，您将在每个查询的末尾看到“REPLICA DB”或“MASTER DB”。

该解决方案使用与 @Lam Phan 解决方案类似的方法，但它保留了所有标准日志记录行为：

• 它不记录 SCHEMA 查询
• 它正确显示触发查询的源文件和行

另请注意，我没有用来ActiveRecord::Base.current_role获取角色，因为它没有显示可靠的信息（即它打印角色writing，但查询转到副本数据库）。

可以使用哈希中的可用信息进一步自定义日志@config，例如host、port、database等。