2 files changed, 49 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/core.rb b/activerecord/lib/active_record/core.rb
index 481159e501..88810cb328 100644
--- a/activerecord/lib/active_record/core.rb
+++ b/activerecord/lib/active_record/core.rb
@@ -18,6 +18,13 @@ module ActiveRecord
       mattr_accessor :logger, instance_writer: false
 
       ##
+      # :singleton-method:
+      #
+      # Specifies if the methods calling database queries should be logged below
+      # their relevant queries. Defaults to false.
+      mattr_accessor :verbose_query_logs, instance_writer: false, default: false
+
+      ##
       # Contains the database configuration - as is typically stored in config/database.yml -
       # as a Hash.
       #
diff --git a/activerecord/lib/active_record/log_subscriber.rb b/activerecord/lib/active_record/log_subscriber.rb
index 405f3a30c6..ba3419be6c 100644
--- a/activerecord/lib/active_record/log_subscriber.rb
+++ b/activerecord/lib/active_record/log_subscriber.rb
@@ -90,6 +90,48 @@ module ActiveRecord
       def logger
         ActiveRecord::Base.logger
       end
+
+      def debug(progname = nil, &block)
+        return unless super
+
+        if ActiveRecord::Base.verbose_query_logs
+          log_query_source
+        end
+      end
+
+      def log_query_source
+        source_line, line_number = extract_callstack(caller_locations)
+
+        if source_line
+          if defined?(::Rails.root)
+            app_root = "#{::Rails.root.to_s}/".freeze
+            source_line = source_line.sub(app_root, "")
+          end
+
+          logger.debug("  ↳ #{ source_line }:#{ line_number }")
+        end
+      end
+
+      def extract_callstack(callstack)
+        line = callstack.find do |frame|
+          frame.absolute_path && !ignored_callstack(frame.absolute_path)
+        end
+
+        offending_line = line || callstack.first
+
+        [
+          offending_line.path,
+          offending_line.lineno,
+          offending_line.label
+        ]
+      end
+
+      RAILS_GEM_ROOT = File.expand_path("../../../..", __FILE__) + "/"
+
+      def ignored_callstack(path)
+        path.start_with?(RAILS_GEM_ROOT) ||
+        path.start_with?(RbConfig::CONFIG["rubylibdir"])
+      end
   end
 end