1 files changed, 14 insertions, 8 deletions
diff --git a/activerecord/lib/active_record/explain.rb b/activerecord/lib/active_record/explain.rb
index 01cacf6153..9e0390bed1 100644
--- a/activerecord/lib/active_record/explain.rb
+++ b/activerecord/lib/active_record/explain.rb
@@ -1,12 +1,12 @@
-require 'active_support/core_ext/class/attribute'
+require 'active_support/lazy_load_hooks'
 
 module ActiveRecord
+  ActiveSupport.on_load(:active_record_config) do
+    mattr_accessor :auto_explain_threshold_in_seconds, instance_accessor: false
+  end
+
   module Explain
-    def self.extended(base)
-      # If a query takes longer than these many seconds we log its query plan
-      # automatically. nil disables this feature.
-      base.config_attribute :auto_explain_threshold_in_seconds, :global => true
-    end
+    delegate :auto_explain_threshold_in_seconds, :auto_explain_threshold_in_seconds=, to: 'ActiveRecord::Model'
 
     # If auto explain is enabled, this method triggers EXPLAIN logging for the
     # queries triggered by the block if it takes more than the threshold as a
@@ -52,7 +52,7 @@ module ActiveRecord
     # Makes the adapter execute EXPLAIN for the tuples of queries and bindings.
     # Returns a formatted string ready to be logged.
     def exec_explain(queries) # :nodoc:
-      queries && queries.map do |sql, bind|
+      str = queries && queries.map do |sql, bind|
         [].tap do |msg|
           msg << "EXPLAIN for: #{sql}"
           unless bind.empty?
@@ -62,6 +62,12 @@ module ActiveRecord
           msg << connection.explain(sql, bind)
         end.join("\n")
       end.join("\n")
+
+      # Overriding inspect to be more human readable, specially in the console.
+      def str.inspect
+        self
+      end
+      str
     end
 
     # Silences automatic EXPLAIN logging for the duration of the block.
@@ -70,7 +76,7 @@ module ActiveRecord
     # the threshold is set to 0.
     #
     # As the name of the method suggests this only applies to automatic
-    # EXPLAINs, manual calls to +ActiveRecord::Relation#explain+ run.
+    # EXPLAINs, manual calls to <tt>ActiveRecord::Relation#explain</tt> run.
     def silence_auto_explain
       current = Thread.current
       original, current[:available_queries_for_explain] = current[:available_queries_for_explain], false