diff --git a/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb b/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb
index 0589e6b447..c8c3fcb22a 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb
@@ -107,20 +107,6 @@ module ActiveRecord
         exec_delete(to_sql(arel, binds), name, binds)
       end
 
-      # Checks whether there is currently no transaction active. This is done
-      # by querying the database driver, and does not use the transaction
-      # house-keeping information recorded by #increment_open_transactions and
-      # friends.
-      #
-      # Returns true if there is no transaction active, false if there is a
-      # transaction active, and nil if this information is unknown.
-      #
-      # Not all adapters supports transaction state introspection. Currently,
-      # only the PostgreSQL adapter supports this.
-      def outside_transaction?
-        nil
-      end
-
       # Returns +true+ when the connection adapter supports prepared statement
       # caching, otherwise returns +false+
       def supports_statement_cache?
@@ -173,7 +159,7 @@ module ActiveRecord
         options.assert_valid_keys :requires_new, :joinable
 
         if !options[:requires_new] && current_transaction.joinable?
-          within_existing_transaction { yield }
+          yield
         else
           within_new_transaction(options) { yield }
         end
@@ -185,27 +171,17 @@ module ActiveRecord
         begin_transaction(options)
         yield
       rescue Exception => error
-        rollback_transaction unless outside_transaction?
+        rollback_transaction
         raise
       ensure
-        if outside_transaction?
-          reset_transaction
-        else
-          begin
-            commit_transaction unless error
-          rescue Exception => e
-            rollback_transaction
-            raise
-          end
+        begin
+          commit_transaction unless error
+        rescue Exception => e
+          rollback_transaction
+          raise
         end
       end
 
-      def within_existing_transaction #:nodoc:
-        yield
-      ensure
-        reset_transaction if outside_transaction?
-      end
-
       def current_transaction #:nodoc:
         @transaction
       end
@@ -228,7 +204,7 @@ module ActiveRecord
         @transaction = @transaction.rollback
       end
 
-      def reset_transaction
+      def reset_transaction #:nodoc:
         @transaction = ClosedTransaction.new(self)
       end
 
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb b/activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb
index eb3084e066..c8437c18cc 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb
@@ -1,3 +1,5 @@
+require 'active_support/deprecation'
+
 module ActiveRecord
   module ConnectionAdapters
     class PostgreSQLAdapter < AbstractAdapter
@@ -214,6 +216,10 @@ module ActiveRecord
         end
 
         def outside_transaction?
+          ActiveSupport::Deprecation.warn(
+            "#outside_transaction? is deprecated. This method was only really used " \
+            "internally, but you can use #transaction_open? instead."
+          )
           @connection.transaction_status == PGconn::PQTRANS_IDLE
         end
 
diff --git a/activerecord/test/cases/transactions_test.rb b/activerecord/test/cases/transactions_test.rb
index e618c0984e..0b5fda3817 100644
--- a/activerecord/test/cases/transactions_test.rb
+++ b/activerecord/test/cases/transactions_test.rb
@@ -349,7 +349,6 @@ class TransactionTest < ActiveRecord::TestCase
   def test_rollback_when_commit_raises
     Topic.connection.expects(:begin_db_transaction)
     Topic.connection.expects(:commit_db_transaction).raises('OH NOES')
-    Topic.connection.expects(:outside_transaction?).returns(false)
     Topic.connection.expects(:rollback_db_transaction)
 
     assert_raise RuntimeError do
@@ -398,36 +397,11 @@ class TransactionTest < ActiveRecord::TestCase
 
   if current_adapter?(:PostgreSQLAdapter) && defined?(PGconn::PQTRANS_IDLE)
     def test_outside_transaction_works
-      assert Topic.connection.outside_transaction?
+      assert assert_deprecated { Topic.connection.outside_transaction? }
       Topic.connection.begin_db_transaction
-      assert !Topic.connection.outside_transaction?
+      assert assert_deprecated { !Topic.connection.outside_transaction? }
       Topic.connection.rollback_db_transaction
-      assert Topic.connection.outside_transaction?
-    end
-
-    def test_rollback_wont_be_executed_if_no_transaction_active
-      assert_raise RuntimeError do
-        Topic.transaction do
-          Topic.connection.rollback_db_transaction
-          Topic.connection.expects(:rollback_db_transaction).never
-          raise "Rails doesn't scale!"
-        end
-      end
-    end
-
-    def test_open_transactions_count_is_reset_to_zero_if_no_transaction_active
-      Topic.transaction do
-        Topic.transaction do
-          Topic.connection.rollback_db_transaction
-        end
-        assert_equal 0, Topic.connection.open_transactions
-      end
-      assert_equal 0, Topic.connection.open_transactions
-
-      Topic.transaction do
-        Topic.connection.rollback_db_transaction
-      end
-      assert_equal 0, Topic.connection.open_transactions
+      assert assert_deprecated { Topic.connection.outside_transaction? }
     end
   end