Load db/schema_cache.dump duaring boot time.

activerecord/lib/active_record/connection_adapters/abstract_adapter.rb

@@ -86,6 +86,11 @@ module ActiveRecord
         end
       end
 
+      def schema_cache=(cache)
+        cache.connection = self
+        @schema_cache = cache
+      end
+
       def expire
         @in_use = false
       end

activerecord/lib/active_record/connection_adapters/schema_cache.rb

@@ -2,7 +2,7 @@ module ActiveRecord
   module ConnectionAdapters
     class SchemaCache
       attr_reader :columns, :columns_hash, :primary_keys, :tables
-      attr_reader :connection
+      attr_accessor :connection
 
       def initialize(conn)
         @connection = conn

activerecord/lib/active_record/railtie.rb

@@ -107,7 +107,7 @@ module ActiveRecord
       config.watchable_files.concat ["#{app.root}/db/schema.rb", "#{app.root}/db/structure.sql"]
     end
 
-    config.after_initialize do
+    config.after_initialize do |app|
       ActiveSupport.on_load(:active_record) do
         ActiveRecord::Base.instantiate_observers
 
@@ -115,6 +115,17 @@ module ActiveRecord
           ActiveRecord::Base.instantiate_observers
         end
       end
+
+      ActiveSupport.on_load(:active_record) do
+        if app.config.use_schema_cache_dump
+          filename = File.join(app.config.paths["db"].first, "schema_cache.dump")
+          if File.file?(filename)
+            cache = Marshal.load(open(filename, 'rb') { |f| f.read })
+            ActiveRecord::Base.connection.schema_cache = cache
+          end
+        end
+      end
+
     end
   end
 end

railties/lib/rails/application/configuration.rb

@@ -11,7 +11,7 @@ module Rails
                     :force_ssl, :helpers_paths, :logger, :log_tags, :preload_frameworks,
                     :railties_order, :relative_url_root, :secret_token,
                     :serve_static_assets, :ssl_options, :static_cache_control, :session_options,
-                    :time_zone, :reload_classes_only_on_change
+                    :time_zone, :reload_classes_only_on_change, :use_schema_cache_dump
 
       attr_writer :log_level
       attr_reader :encoding
@@ -41,6 +41,7 @@ module Rails
         @file_watcher                  = ActiveSupport::FileUpdateChecker
         @exceptions_app                = nil
         @autoflush_log                 = true
+        @use_schema_cache_dump         = true
 
         @assets = ActiveSupport::OrderedOptions.new
         @assets.enabled                  = false

railties/test/application/initializers/frameworks_test.rb

@@ -193,5 +193,17 @@ module ApplicationTests
       require "#{app_path}/config/environment"
       assert_nil defined?(ActiveRecord::Base)
     end
+
+    test "use schema cache dump" do
+      Dir.chdir(app_path) do
+        `rails generate model post title:string`
+        `bundle exec rake db:migrate`
+        `bundle exec rake db:schema:cache:dump`
+      end
+      require "#{app_path}/config/environment"
+      ActiveRecord::Base.connection.drop_table("posts") # force drop posts table for test.
+      assert ActiveRecord::Base.connection.schema_cache.tables["posts"]
+    end
+
   end
 end