7 files changed, 53 insertions, 11 deletions
diff --git a/railties/guides/source/active_record_querying.textile b/railties/guides/source/active_record_querying.textile
index 352f23dc01..742aefc32f 100644
--- a/railties/guides/source/active_record_querying.textile
+++ b/railties/guides/source/active_record_querying.textile
@@ -1369,6 +1369,43 @@ EXPLAIN for: SELECT `posts`.* FROM `posts`  WHERE `posts`.`user_id` IN (1)
 
 under MySQL.
 
+h4. 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
+</ruby>
+
+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.
+
+h5. Disabling Automatic EXPLAIN
+
+Automatic EXPLAIN can be selectively silenced with +silence_auto_explain+, which
+is a class and instance method of +ActiveRecord::Base+:
+
+<ruby>
+silence_auto_explain do
+  # no automatic EXPLAIN is triggered here
+end
+</ruby>
+
+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.
+
 h4. Interpreting EXPLAIN
 
 Interpretation of the output of EXPLAIN is beyond the scope of this guide. The
diff --git a/railties/guides/source/active_support_core_extensions.textile b/railties/guides/source/active_support_core_extensions.textile
index 7959a88c5b..6646e9cd05 100644
--- a/railties/guides/source/active_support_core_extensions.textile
+++ b/railties/guides/source/active_support_core_extensions.textile
@@ -1301,7 +1301,7 @@ NOTE: Defined in +active_support/core_ext/string/output_safety.rb+.
 
 h5. Transformation
 
-As a rule of thumb, except perhaps for concatenation as explained above, any method that may change a string gives you an unsafe string. These are +donwcase+, +gsub+, +strip+, +chomp+, +underscore+, etc.
+As a rule of thumb, except perhaps for concatenation as explained above, any method that may change a string gives you an unsafe string. These are +downcase+, +gsub+, +strip+, +chomp+, +underscore+, etc.
 
 In the case of in-place transformations like +gsub!+ the receiver itself becomes unsafe.
 
@@ -2053,6 +2053,16 @@ end
 
 NOTE: Defined in +active_support/core_ext/enumerable.rb+.
 
+h4. +pluck+
+
+The +pluck+ method collects the value of the passed method for each element and returns the result as an array.
+
+<ruby>
+people.pluck(:name) # => [ "David Heinemeier Hansson", "Jamie Heinemeier Hansson" ]
+</ruby>
+
+NOTE: Defined in +active_support/core_ext/enumerable.rb+.
+
 h4. +each_with_object+
 
 The +inject+ method offers iteration with an accumulator:
diff --git a/railties/guides/source/asset_pipeline.textile b/railties/guides/source/asset_pipeline.textile
index 3681501293..8ff1035a1c 100644
--- a/railties/guides/source/asset_pipeline.textile
+++ b/railties/guides/source/asset_pipeline.textile
@@ -410,10 +410,6 @@ For Apache:
 
 <plain>
 <LocationMatch "^/assets/.*$">
-  # Some browsers still send conditional-GET requests if there's a
-  # Last-Modified header or an ETag header even if they haven't
-  # reached the expiry date sent in the Expires header.
-  Header unset Last-Modified
   Header unset ETag
   FileETag None
   # RFC says only cache for 1 year
@@ -429,10 +425,6 @@ location ~ ^/assets/ {
   expires 1y;
   add_header Cache-Control public;
 
-  # Some browsers still send conditional-GET requests if there's a
-  # Last-Modified header or an ETag header even if they haven't
-  # reached the expiry date sent in the Expires header.
-  add_header Last-Modified "";
   add_header ETag "";
   break;
 }
diff --git a/railties/guides/source/command_line.textile b/railties/guides/source/command_line.textile
index 9284a542f3..3fa6c059e1 100644
--- a/railties/guides/source/command_line.textile
+++ b/railties/guides/source/command_line.textile
@@ -391,7 +391,7 @@ Action Pack version       3.2.0.beta
 Active Resource version   3.2.0.beta
 Action Mailer version     3.2.0.beta
 Active Support version    3.2.0.beta
-Middleware                ActionDispatch::Static, Rack::Lock, Rack::Runtime, Rack::MethodOverride, ActionDispatch::RequestId, Rails::Rack::Logger, ActionDispatch::ShowExceptions, ActionDispatch::RemoteIp, ActionDispatch::Reloader, ActionDispatch::Callbacks, ActiveRecord::ConnectionAdapters::ConnectionManagement, ActiveRecord::QueryCache, ActionDispatch::Cookies, ActionDispatch::Session::CookieStore, ActionDispatch::Flash, ActionDispatch::ParamsParser, ActionDispatch::Head, Rack::ConditionalGet, Rack::ETag, ActionDispatch::BestStandardsSupport
+Middleware                ActionDispatch::Static, Rack::Lock, Rack::Runtime, Rack::MethodOverride, ActionDispatch::RequestId, Rails::Rack::Logger, ActionDispatch::ShowExceptions, ActionDispatch::DebugExceptions, ActionDispatch::RemoteIp, ActionDispatch::Reloader, ActionDispatch::Callbacks, ActiveRecord::ConnectionAdapters::ConnectionManagement, ActiveRecord::QueryCache, ActionDispatch::Cookies, ActionDispatch::Session::CookieStore, ActionDispatch::Flash, ActionDispatch::ParamsParser, ActionDispatch::Head, Rack::ConditionalGet, Rack::ETag, ActionDispatch::BestStandardsSupport
 Application root          /home/foobar/commandsapp
 Environment               development
 Database adapter          sqlite3
diff --git a/railties/guides/source/configuring.textile b/railties/guides/source/configuring.textile
index d91011c370..8e65dbccbb 100644
--- a/railties/guides/source/configuring.textile
+++ b/railties/guides/source/configuring.textile
@@ -268,6 +268,8 @@ h4. Configuring Active Record
 
 * +config.active_record.identity_map+ controls whether the identity map is enabled, and is false 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.
+
 The MySQL adapter adds one additional configuration option:
 
 * +ActiveRecord::ConnectionAdapters::MysqlAdapter.emulate_booleans+ controls whether Active Record will consider all +tinyint(1)+ columns in a MySQL database to be booleans and is true by default.
diff --git a/railties/guides/source/performance_testing.textile b/railties/guides/source/performance_testing.textile
index 2440927542..958b13cd9e 100644
--- a/railties/guides/source/performance_testing.textile
+++ b/railties/guides/source/performance_testing.textile
@@ -151,7 +151,7 @@ Performance tests can be run in two modes: Benchmarking and Profiling.
 
 h5. Benchmarking
 
-Benchmarking makes it easy to quickly gather a few metrics about each test tun. By default, each test case is run *4 times* in benchmarking mode.
+Benchmarking makes it easy to quickly gather a few metrics about each test run. By default, each test case is run *4 times* in benchmarking mode.
 
 To run performance tests in benchmarking mode:
 
diff --git a/railties/guides/source/rails_on_rack.textile b/railties/guides/source/rails_on_rack.textile
index d6cbd84b1f..9526526bc7 100644
--- a/railties/guides/source/rails_on_rack.textile
+++ b/railties/guides/source/rails_on_rack.textile
@@ -95,6 +95,7 @@ use ActiveSupport::Cache::Strategy::LocalCache
 use Rack::Runtime
 use Rails::Rack::Logger
 use ActionDispatch::ShowExceptions
+use ActionDispatch::DebugExceptions
 use ActionDispatch::RemoteIp
 use Rack::Sendfile
 use ActionDispatch::Callbacks