5 files changed, 6 insertions, 49 deletions
diff --git a/guides/code/getting_started/config/environments/development.rb b/guides/code/getting_started/config/environments/development.rb
index ed2667ac58..d169e9452c 100644
--- a/guides/code/getting_started/config/environments/development.rb
+++ b/guides/code/getting_started/config/environments/development.rb
@@ -22,10 +22,6 @@ Blog::Application.configure do
   # Only use best-standards-support built into browsers.
   config.action_dispatch.best_standards_support = :builtin
 
-  # Log the query plan for queries taking more than this (works
-  # with SQLite, MySQL, and PostgreSQL).
-  config.active_record.auto_explain_threshold_in_seconds = 0.5
-
   # Raise an error on page load if there are pending migrations
   config.active_record.migration_error = :page_load
 
diff --git a/guides/code/getting_started/config/environments/production.rb b/guides/code/getting_started/config/environments/production.rb
index 58dab2a319..368a735122 100644
--- a/guides/code/getting_started/config/environments/production.rb
+++ b/guides/code/getting_started/config/environments/production.rb
@@ -72,10 +72,6 @@ Blog::Application.configure do
   # Send deprecation notices to registered listeners.
   config.active_support.deprecation = :notify
 
-  # Log the query plan for queries taking more than this (works
-  # with SQLite, MySQL, and PostgreSQL).
-  # config.active_record.auto_explain_threshold_in_seconds = 0.5
-
   # Disable automatic flushing of the log to improve performance.
   # config.autoflush_log = false
 
diff --git a/guides/source/active_record_querying.md b/guides/source/active_record_querying.md
index 62d6294ae5..bc3b1669d2 100644
--- a/guides/source/active_record_querying.md
+++ b/guides/source/active_record_querying.md
@@ -1609,45 +1609,6 @@ EXPLAIN for: SELECT `posts`.* FROM `posts`  WHERE `posts`.`user_id` IN (1)
 
 under MySQL.
 
-### Automatic EXPLAIN
-
-Active Record is able to run EXPLAIN automatically on slow queries and log its
-output. This feature is controlled by the configuration parameter
-
-```ruby
-config.active_record.auto_explain_threshold_in_seconds
-```
-
-If set to a number, any query exceeding those many seconds will have its EXPLAIN
-automatically triggered and logged. In the case of relations, the threshold is
-compared to the total time needed to fetch records. So, a relation is seen as a
-unit of work, no matter whether the implementation of eager loading involves
-several queries under the hood.
-
-A threshold of `nil` disables automatic EXPLAINs.
-
-The default threshold in development mode is 0.5 seconds, and `nil` in test and
-production modes.
-
-INFO. Automatic EXPLAIN gets disabled if Active Record has no logger, regardless
-of the value of the threshold.
-
-#### Disabling Automatic EXPLAIN
-
-Automatic EXPLAIN can be selectively silenced with `ActiveRecord::Base.silence_auto_explain`:
-
-```ruby
-ActiveRecord::Base.silence_auto_explain do
-  # no automatic EXPLAIN is triggered here
-end
-```
-
-That may be useful for queries you know are slow but fine, like a heavyweight
-report of an admin interface.
-
-As its name suggests, `silence_auto_explain` only silences automatic EXPLAINs.
-Explicit calls to `ActiveRecord::Relation#explain` run.
-
 ### Interpreting EXPLAIN
 
 Interpretation of the output of EXPLAIN is beyond the scope of this guide. The
diff --git a/guides/source/configuring.md b/guides/source/configuring.md
index be46e15078..dbbeec7126 100644
--- a/guides/source/configuring.md
+++ b/guides/source/configuring.md
@@ -268,8 +268,6 @@ config.middleware.delete "Rack::MethodOverride"
 
 * `config.active_record.lock_optimistically` controls whether Active Record will use optimistic locking and is true by default.
 
-* `config.active_record.auto_explain_threshold_in_seconds` configures the threshold for automatic EXPLAINs (`nil` disables this feature). Queries exceeding the threshold get their query plan logged. Default is 0.5 in development mode.
-
 * +config.active_record.cache_timestamp_format+ controls the format of the timestamp value in the cache key. Default is +:number+.
 
 The MySQL adapter adds one additional configuration option:
diff --git a/guides/source/upgrading_ruby_on_rails.md b/guides/source/upgrading_ruby_on_rails.md
index 18baed55b5..915a008a92 100644
--- a/guides/source/upgrading_ruby_on_rails.md
+++ b/guides/source/upgrading_ruby_on_rails.md
@@ -45,6 +45,12 @@ Rails 4.0 no longer supports loading plugins from `vendor/plugins`. You must rep
 
 * Rails 4.0 has changed `serialized_attributes` and `attr_readonly` to class methods only. Now you shouldn't use instance methods, it's deprecated. You must change them, e.g. `self.serialized_attributes` to `self.class.serialized_attributes`.
 
+* Rails 4.0 has removed `attr_accessible` and `attr_protected` feature in favor of Strong Parameters. You can use the [Protected Attributes gem](https://github.com/rails/protected_attributes) to a smoothly upgrade path.
+
+### Active Resource
+
+Rails 4.0 extracted Active Resource to its our gem. If you still need the feature you can add the [Active Resource gem](https://github.com/rails/activeresource) in your Gemfile.
+
 ### Active Model
 
 * Rails 4.0 has changed how errors attach with the `ActiveModel::Validations::ConfirmationValidator`. Now when confirmation validations fail the error will be attached to `:#{attribute}_confirmation` instead of `attribute`.