Merge branch 'master' into laurocaetano-fix_send_file

* master: (536 commits)
  doc, API example on how to use `Model#exists?` with multiple IDs. [ci skip]
  Restore DATABASE_URL even if it's nil in connection_handler test
  [ci skip] - error_messages_for has been deprecated since 2.3.8 - lets reduce any confusion for users
  Ensure Active Record connection consistency
  Revert "ask the fixture set for the sql statements"
  Check `respond_to` before delegation due to: https://github.com/ruby/ruby/commit/d781caaf313b8649948c107bba277e5ad7307314
  Adding Hash#compact and Hash#compact! methods
  MySQL version 4.1 was EOL on December 31, 2009 We should at least recommend modern versions of MySQL to users.
  clear cache on body close so that cache remains during rendering
  add a more restricted codepath for templates fixes #13390
  refactor generator tests to use block form of Tempfile
  Fix typo [ci skip]
  Move finish_template as the last public method in the generator
  Minor typos fix [ci skip]
  make `change_column_null` reversible. Closes #13576.
  create/drop test and development databases only if RAILS_ENV is nil
  Revert "Speedup String#to"
  typo fix in test name. [ci skip].
  `core_ext/string/access.rb` test what we are documenting.
  Fix typo in image_tag documentation
  ...

Conflicts:
	actionpack/CHANGELOG.md

17 files changed, 345 insertions, 118 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
index cfdcae7f63..cebe741daa 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
@@ -86,7 +86,7 @@ module ActiveRecord
           end
         end
 
-        # Return the number of threads currently waiting on this
+        # Returns the number of threads currently waiting on this
         # queue.
         def num_waiting
           synchronize do
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 1a323b6a9c..c90915c509 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb
@@ -286,10 +286,6 @@ module ActiveRecord
       # Inserts the given fixture into the table. Overridden in adapters that require
       # something beyond a simple insert (eg. Oracle).
       def insert_fixture(fixture, table_name)
-        execute fixture_sql(fixture, table_name), 'Fixture Insert'
-      end
-
-      def fixture_sql(fixture, table_name)
         columns = schema_cache.columns_hash(table_name)
 
         key_list   = []
@@ -298,7 +294,7 @@ module ActiveRecord
           quote(value, columns[name])
         end
 
-        "INSERT INTO #{quote_table_name(table_name)} (#{key_list.join(', ')}) VALUES (#{value_list.join(', ')})"
+        execute "INSERT INTO #{quote_table_name(table_name)} (#{key_list.join(', ')}) VALUES (#{value_list.join(', ')})", 'Fixture Insert'
       end
 
       def empty_insert_statement_value
@@ -346,7 +342,7 @@ module ActiveRecord
 
       protected
 
-        # Return a subquery for the given key using the join information.
+        # Returns a subquery for the given key using the join information.
         def subquery_for(key, select)
           subselect = select.clone
           subselect.projections = [key]
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb b/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb
index 8399232d73..adc23a6674 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb
@@ -31,8 +31,8 @@ module ActiveRecord
         old, @query_cache_enabled = @query_cache_enabled, true
         yield
       ensure
-        clear_query_cache
         @query_cache_enabled = old
+        clear_query_cache unless @query_cache_enabled
       end
 
       def enable_query_cache!
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb b/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb
index 552a22d28a..75501852ed 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb
@@ -43,7 +43,9 @@ module ActiveRecord
       # SQLite does not understand dates, so this method will convert a Date
       # to a String.
       def type_cast(value, column)
-        return value.id if value.respond_to?(:quoted_id)
+        if value.respond_to?(:quoted_id) && value.respond_to?(:id)
+          return value.id
+        end
 
         case value
         when String, ActiveSupport::Multibyte::Chars
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_creation.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_creation.rb
index 7c330a2f25..a51691bfa8 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_creation.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_creation.rb
@@ -34,9 +34,10 @@ module ActiveRecord
 
           def visit_TableDefinition(o)
             create_sql = "CREATE#{' TEMPORARY' if o.temporary} TABLE "
-            create_sql << "#{quote_table_name(o.name)} ("
-            create_sql << o.columns.map { |c| accept c }.join(', ')
-            create_sql << ") #{o.options}"
+            create_sql << "#{quote_table_name(o.name)} "
+            create_sql << "(#{o.columns.map { |c| accept c }.join(', ')}) " unless o.as
+            create_sql << "#{o.options}"
+            create_sql << " AS #{@conn.to_sql(o.as)}" if o.as
             create_sql
           end
 
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
index 063b19871a..c39bf15e83 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
@@ -49,14 +49,15 @@ module ActiveRecord
       # An array of ColumnDefinition objects, representing the column changes
       # that have been defined.
       attr_accessor :indexes
-      attr_reader :name, :temporary, :options
+      attr_reader :name, :temporary, :options, :as
 
-      def initialize(types, name, temporary, options)
+      def initialize(types, name, temporary, options, as = nil)
         @columns_hash = {}
         @indexes = {}
         @native = types
         @temporary = temporary
         @options = options
+        @as = as
         @name = name
       end
 
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
index 6268ae4875..88bf15bc18 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
@@ -131,6 +131,9 @@ module ActiveRecord
       # [<tt>:force</tt>]
       #   Set to true to drop the table before creating it.
       #   Defaults to false.
+      # [<tt>:as</tt>]
+      #   SQL to use to generate the table. When this option is used, the block is
+      #   ignored, as are the <tt>:id</tt> and <tt>:primary_key</tt> options.
       #
       # ====== Add a backend specific option to the generated SQL (MySQL)
       #
@@ -169,19 +172,31 @@ module ActiveRecord
       #     supplier_id int
       #   )
       #
+      # ====== Create a temporary table based on a query
+      #
+      #   create_table(:long_query, temporary: true,
+      #     as: "SELECT * FROM orders INNER JOIN line_items ON order_id=orders.id")
+      #
+      # generates:
+      #
+      #   CREATE TEMPORARY TABLE long_query AS
+      #     SELECT * FROM orders INNER JOIN line_items ON order_id=orders.id
+      #
       # See also TableDefinition#column for details on how to create columns.
       def create_table(table_name, options = {})
-        td = create_table_definition table_name, options[:temporary], options[:options]
+        td = create_table_definition table_name, options[:temporary], options[:options], options[:as]
 
-        unless options[:id] == false
-          pk = options.fetch(:primary_key) {
-            Base.get_primary_key table_name.to_s.singularize
-          }
+        if !options[:as]
+          unless options[:id] == false
+            pk = options.fetch(:primary_key) {
+              Base.get_primary_key table_name.to_s.singularize
+            }
 
-          td.primary_key pk, options.fetch(:id, :primary_key), options
-        end
+            td.primary_key pk, options.fetch(:id, :primary_key), options
+          end
 
-        yield td if block_given?
+          yield td if block_given?
+        end
 
         if options[:force] && table_exists?(table_name)
           drop_table(table_name, options)
@@ -690,7 +705,7 @@ module ActiveRecord
 
           column_type_sql
         else
-          type
+          type.to_s
         end
       end
 
@@ -699,7 +714,7 @@ module ActiveRecord
       # require the order columns appear in the SELECT.
       #
       #   columns_for_distinct("posts.id", ["posts.created_at desc"])
-      def columns_for_distinct(columns, orders) # :nodoc:
+      def columns_for_distinct(columns, orders) #:nodoc:
         columns
       end
 
@@ -721,6 +736,10 @@ module ActiveRecord
         remove_column table_name, :created_at
       end
 
+      def update_table_definition(table_name, base) #:nodoc:
+        Table.new(table_name, base)
+      end
+
       protected
         def add_index_sort_order(option_strings, column_names, options = {})
           if options.is_a?(Hash) && order = options[:order]
@@ -826,17 +845,13 @@ module ActiveRecord
         end
 
       private
-      def create_table_definition(name, temporary, options)
-        TableDefinition.new native_database_types, name, temporary, options
+      def create_table_definition(name, temporary, options, as = nil)
+        TableDefinition.new native_database_types, name, temporary, options, as
       end
 
       def create_alter_table(name)
         AlterTable.new create_table_definition(name, false, {})
       end
-
-      def update_table_definition(table_name, base)
-        Table.new(table_name, base)
-      end
     end
   end
 end
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
index e3270e734f..7768c24967 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -148,7 +148,7 @@ module ActiveRecord
       QUOTED_TRUE, QUOTED_FALSE = '1', '0'
 
       NATIVE_DATABASE_TYPES = {
-        :primary_key => "int(11) DEFAULT NULL auto_increment PRIMARY KEY",
+        :primary_key => "int(11) auto_increment PRIMARY KEY",
         :string      => { :name => "varchar", :limit => 255 },
         :text        => { :name => "text" },
         :integer     => { :name => "int", :limit => 4 },
@@ -303,12 +303,6 @@ module ActiveRecord
         else
           log(sql, name) { @connection.query(sql) }
         end
-      rescue ActiveRecord::StatementInvalid => exception
-        if exception.message.split(":").first =~ /Packets out of order/
-          raise ActiveRecord::StatementInvalid.new("'Packets out of order' error was received from the database. Please update your mysql bindings (gem install mysql) and read http://dev.mysql.com/doc/mysql/en/password-hashing.html for more information. If you're on Windows, use the Instant Rails installer to get the updated mysql bindings.", exception.original_exception)
-        else
-          raise
-        end
       end
 
       # MysqlAdapter has to free a result after using it, so we use this method to write
@@ -492,6 +486,10 @@ module ActiveRecord
         rename_table_indexes(table_name, new_name)
       end
 
+      def drop_table(table_name, options = {})
+        execute "DROP#{' TEMPORARY' if options[:temporary]} TABLE #{quote_table_name(table_name)}"
+      end
+
       def rename_index(table_name, old_name, new_name)
         if (version[0] == 5 && version[1] >= 7) || version[0] >= 6
           execute "ALTER TABLE #{quote_table_name(table_name)} RENAME INDEX #{quote_table_name(old_name)} TO #{quote_table_name(new_name)}"
diff --git a/activerecord/lib/active_record/connection_adapters/connection_specification.rb b/activerecord/lib/active_record/connection_adapters/connection_specification.rb
index 64fc9e95d8..3f8b14bf67 100644
--- a/activerecord/lib/active_record/connection_adapters/connection_specification.rb
+++ b/activerecord/lib/active_record/connection_adapters/connection_specification.rb
@@ -13,41 +13,146 @@ module ActiveRecord
         @config = original.config.dup
       end
 
+      # Expands a connection string into a hash.
+      class ConnectionUrlResolver # :nodoc:
+
+        # == Example
+        #
+        #   url = "postgresql://foo:bar@localhost:9000/foo_test?pool=5&timeout=3000"
+        #   ConnectionUrlResolver.new(url).to_hash
+        #   # => {
+        #     "adapter"  => "postgresql",
+        #     "host"     => "localhost",
+        #     "port"     => 9000,
+        #     "database" => "foo_test",
+        #     "username" => "foo",
+        #     "password" => "bar",
+        #     "pool"     => "5",
+        #     "timeout"  => "3000"
+        #   }
+        def initialize(url)
+          raise "Database URL cannot be empty" if url.blank?
+          @uri     = URI.parse(url)
+          @adapter = @uri.scheme
+          @adapter = "postgresql" if @adapter == "postgres"
+          @query   = @uri.query || ''
+        end
+
+        # Converts the given URL to a full connection hash.
+        def to_hash
+          config = raw_config.reject { |_,value| value.blank? }
+          config.map { |key,value| config[key] = uri_parser.unescape(value) if value.is_a? String }
+          config
+        end
+
+        private
+
+        def uri
+          @uri
+        end
+
+        def uri_parser
+          @uri_parser ||= URI::Parser.new
+        end
+
+        # Converts the query parameters of the URI into a hash.
+        #
+        #   "localhost?pool=5&reap_frequency=2"
+        #   # => { "pool" => "5", "reap_frequency" => "2" }
+        #
+        # returns empty hash if no query present.
+        #
+        #   "localhost"
+        #   # => {}
+        def query_hash
+          Hash[@query.split("&").map { |pair| pair.split("=") }]
+        end
+
+        def raw_config
+          query_hash.merge({
+            "adapter"  => @adapter,
+            "username" => uri.user,
+            "password" => uri.password,
+            "port"     => uri.port,
+            "database" => database,
+            "host"     => uri.host })
+        end
+
+        # Returns name of the database.
+        # Sqlite3 expects this to be a full path or `:memory:`.
+        def database
+          if @adapter == 'sqlite3'
+            if '/:memory:' == uri.path
+              ':memory:'
+            else
+              uri.path
+            end
+          else
+            uri.path.sub(%r{^/},"")
+          end
+        end
+      end
+
       ##
-      # Builds a ConnectionSpecification from user input
+      # Builds a ConnectionSpecification from user input.
       class Resolver # :nodoc:
-        attr_reader :config, :klass, :configurations
+        attr_reader :configurations
 
-        def initialize(config, configurations)
-          @config         = config
+        # Accepts a hash two layers deep, keys on the first layer represent
+        # environments such as "production". Keys must be strings.
+        def initialize(configurations)
           @configurations = configurations
         end
 
-        def spec
-          case config
-          when nil
-            raise AdapterNotSpecified unless defined?(Rails.env)
-            resolve_string_connection Rails.env
-          when Symbol, String
-            resolve_string_connection config.to_s
-          when Hash
-            resolve_hash_connection config
+        # Returns a hash with database connection information.
+        #
+        # == Examples
+        #
+        # Full hash Configuration.
+        #
+        #   configurations = { "production" => { "host" => "localhost", "database" => "foo", "adapter" => "sqlite3" } }
+        #   Resolver.new(configurations).resolve(:production)
+        #   # => { "host" => "localhost", "database" => "foo", "adapter" => "sqlite3"}
+        #
+        # Initialized with URL configuration strings.
+        #
+        #   configurations = { "production" => "postgresql://localhost/foo" }
+        #   Resolver.new(configurations).resolve(:production)
+        #   # => { "host" => "localhost", "database" => "foo", "adapter" => "postgresql" }
+        #
+        def resolve(config)
+          if config
+            resolve_connection config
+          elsif env = ActiveRecord::ConnectionHandling::RAILS_ENV.call
+            resolve_env_connection env.to_sym
+          else
+            raise AdapterNotSpecified
           end
         end
 
-        private
-        def resolve_string_connection(spec) # :nodoc:
-          hash = configurations.fetch(spec) do |k|
-            connection_url_to_hash(k)
+        # Expands each key in @configurations hash into fully resolved hash
+        def resolve_all
+          config = configurations.dup
+          config.each do |key, value|
+            config[key] = resolve(value) if value
           end
-
-          raise(AdapterNotSpecified, "#{spec} database is not configured") unless hash
-
-          resolve_hash_connection hash
+          config
         end
 
-        def resolve_hash_connection(spec) # :nodoc:
-          spec = spec.symbolize_keys
+        # Returns an instance of ConnectionSpecification for a given adapter.
+        # Accepts a hash one layer deep that contains all connection information.
+        #
+        # == Example
+        #
+        #   config = { "production" => { "host" => "localhost", "database" => "foo", "adapter" => "sqlite3" } }
+        #   spec = Resolver.new(config).spec(:production)
+        #   spec.adapter_method
+        #   # => "sqlite3"
+        #   spec.config
+        #   # => { "host" => "localhost", "database" => "foo", "adapter" => "sqlite3" }
+        #
+        def spec(config)
+          spec = resolve(config).symbolize_keys
 
           raise(AdapterNotSpecified, "database configuration does not specify adapter") unless spec.key?(:adapter)
 
@@ -61,35 +166,87 @@ module ActiveRecord
           end
 
           adapter_method = "#{spec[:adapter]}_connection"
-
           ConnectionSpecification.new(spec, adapter_method)
         end
 
-        def connection_url_to_hash(url) # :nodoc:
-          config = URI.parse url
-          adapter = config.scheme
-          adapter = "postgresql" if adapter == "postgres"
-          spec = { :adapter  => adapter,
-                   :username => config.user,
-                   :password => config.password,
-                   :port     => config.port,
-                   :database => config.path.sub(%r{^/},""),
-                   :host     => config.host }
-
-          spec.reject!{ |_,value| value.blank? }
-
-          uri_parser = URI::Parser.new
-
-          spec.map { |key,value| spec[key] = uri_parser.unescape(value) if value.is_a?(String) }
+        private
 
-          if config.query
-            options = Hash[config.query.split("&").map{ |pair| pair.split("=") }].symbolize_keys
+        # Returns fully resolved connection, accepts hash, string or symbol.
+        # Always returns a hash.
+        #
+        # == Examples
+        #
+        # Symbol representing current environment.
+        #
+        #   Resolver.new("production" => {}).resolve_connection(:production)
+        #   # => {}
+        #
+        # One layer deep hash of connection values.
+        #
+        #   Resolver.new({}).resolve_connection("adapter" => "sqlite3")
+        #   # => { "adapter" => "sqlite3" }
+        #
+        # Connection URL.
+        #
+        #   Resolver.new({}).resolve_connection("postgresql://localhost/foo")
+        #   # => { "host" => "localhost", "database" => "foo", "adapter" => "postgresql" }
+        #
+        def resolve_connection(spec)
+          case spec
+          when Symbol, String
+            resolve_env_connection spec
+          when Hash
+            resolve_hash_connection spec
+          end
+        end
 
-            spec.merge!(options)
+        # Takes the environment such as `:production` or `:development`.
+        # This requires that the @configurations was initialized with a key that
+        # matches.
+        #
+        #
+        #   Resolver.new("production" => {}).resolve_env_connection(:production)
+        #   # => {}
+        #
+        # Takes a connection URL.
+        #
+        #   Resolver.new({}).resolve_env_connection("postgresql://localhost/foo")
+        #   # => { "host" => "localhost", "database" => "foo", "adapter" => "postgresql" }
+        #
+        def resolve_env_connection(spec)
+          # Rails has historically accepted a string to mean either
+          # an environment key or a URL spec, so we have deprecated
+          # this ambiguous behaviour and in the future this function
+          # can be removed in favor of resolve_string_connection and
+          # resolve_symbol_connection.
+          if config = configurations[spec.to_s]
+            if spec.is_a?(String)
+              ActiveSupport::Deprecation.warn "Passing a string to ActiveRecord::Base.establish_connection " \
+                "for a configuration lookup is deprecated, please pass a symbol (#{spec.to_sym.inspect}) instead"
+            end
+            resolve_connection(config)
+          elsif spec.is_a?(String)
+            resolve_string_connection(spec)
+          else
+            raise(AdapterNotSpecified, "'#{spec}' database is not configured. Available configuration: #{configurations.inspect}")
           end
+        end
 
+        # Accepts a hash. Expands the "url" key that contains a
+        # URL database connection to a full connection
+        # hash and merges with the rest of the hash.
+        # Connection details inside of the "url" key win any merge conflicts
+        def resolve_hash_connection(spec)
+          if url = spec.delete("url")
+            connection_hash = resolve_string_connection(url)
+            spec.merge!(connection_hash)
+          end
           spec
         end
+
+        def resolve_string_connection(url)
+          ConnectionUrlResolver.new(url).to_hash
+        end
       end
     end
   end
diff --git a/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb b/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb
index e790f731ea..6d8e994654 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb
@@ -18,6 +18,12 @@ module ActiveRecord
       client = Mysql2::Client.new(config)
       options = [config[:host], config[:username], config[:password], config[:database], config[:port], config[:socket], 0]
       ConnectionAdapters::Mysql2Adapter.new(client, logger, options, config)
+    rescue Mysql2::Error => error
+      if error.message.include?("Unknown database")
+        raise ActiveRecord::NoDatabaseError.new(error.message)
+      else
+        raise error
+      end
     end
   end
 
diff --git a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
index c4dcba0501..7dbaa272a3 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
@@ -34,6 +34,12 @@ module ActiveRecord
       default_flags |= Mysql::CLIENT_FOUND_ROWS if Mysql.const_defined?(:CLIENT_FOUND_ROWS)
       options = [host, username, password, database, port, socket, default_flags]
       ConnectionAdapters::MysqlAdapter.new(mysql, logger, options, config)
+    rescue Mysql::Error => error
+      if error.message.include?("Unknown database")
+        raise ActiveRecord::NoDatabaseError.new(error.message)
+      else
+        raise error
+      end
     end
   end
 
@@ -419,14 +425,19 @@ module ActiveRecord
 
           if result
             types = {}
+            fields = []
             result.fetch_fields.each { |field|
+              field_name = field.name
+              fields << field_name
+
               if field.decimals > 0
-                types[field.name] = Fields::Decimal.new
+                types[field_name] = Fields::Decimal.new
               else
-                types[field.name] = Fields.find_type field
+                types[field_name] = Fields.find_type field
               end
             }
-            result_set = ActiveRecord::Result.new(types.keys, result.to_a, types)
+
+            result_set = ActiveRecord::Result.new(fields, result.to_a, types)
             result.free
           else
             result_set = ActiveRecord::Result.new([], [])
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/cast.rb b/activerecord/lib/active_record/connection_adapters/postgresql/cast.rb
index bf34f2bdae..35ce881302 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/cast.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/cast.rb
@@ -144,7 +144,7 @@ module ActiveRecord
 
           def quote_and_escape(value)
             case value
-            when "NULL"
+            when "NULL", Numeric
               value
             else
               "\"#{value.gsub(/"/,"\\\"")}\""
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 fa173d13a2..f349c37724 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb
@@ -142,7 +142,7 @@ module ActiveRecord
           fields.each_with_index do |fname, i|
             ftype = result.ftype i
             fmod  = result.fmod i
-            types[fname] = OID::TYPE_MAP.fetch(ftype, fmod) { |oid, mod|
+            types[fname] = type_map.fetch(ftype, fmod) { |oid, mod|
               warn "unknown OID: #{fname}(#{oid}) (#{sql})"
               OID::Identity.new
             }
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid.rb
index 2a9547fd10..fae260a921 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid.rb
@@ -301,11 +301,9 @@ module ActiveRecord
           end
         end
 
-        TYPE_MAP = TypeMap.new # :nodoc:
-
-        # When the PG adapter connects, the pg_type table is queried.  The
+        # When the PG adapter connects, the pg_type table is queried. The
         # key of this hash maps to the `typname` column from the table.
-        # TYPE_MAP is then dynamically built with oids as the key and type
+        # type_map is then dynamically built with oids as the key and type
         # objects as values.
         NAMES = Hash.new { |h,k| # :nodoc:
           h[k] = OID::Identity.new
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
index 5dc70a5ad1..571257f6dd 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
@@ -172,7 +172,7 @@ module ActiveRecord
         def columns(table_name)
           # Limit, precision, and scale are all handled by the superclass.
           column_definitions(table_name).map do |column_name, type, default, notnull, oid, fmod|
-            oid = OID::TYPE_MAP.fetch(oid.to_i, fmod.to_i) {
+            oid = type_map.fetch(oid.to_i, fmod.to_i) {
               OID::Identity.new
             }
             PostgreSQLColumn.new(column_name, default, oid, type, notnull == 'f')
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
index adeb57d913..7e188907e1 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
@@ -46,7 +46,7 @@ module ActiveRecord
     # PostgreSQL-specific extensions to column definitions in a table.
     class PostgreSQLColumn < Column #:nodoc:
       attr_accessor :array
-      # Instantiates a new PostgreSQL column definition in a table.
+
       def initialize(name, default, oid_type, sql_type = nil, null = true)
         @oid_type = oid_type
         default_value     = self.class.extract_value_from_default(default)
@@ -62,6 +62,14 @@ module ActiveRecord
         @default_function = default if has_default_function?(default_value, default)
       end
 
+      def number?
+        !array && super
+      end
+
+      def text?
+        !array && super
+      end
+
       # :stopdoc:
       class << self
         include ConnectionAdapters::PostgreSQLColumn::Cast
@@ -565,7 +573,8 @@ module ActiveRecord
           raise "Your version of PostgreSQL (#{postgresql_version}) is too old, please upgrade!"
         end
 
-        initialize_type_map
+        @type_map = OID::TypeMap.new
+        initialize_type_map(type_map)
         @local_tz = execute('SHOW TIME ZONE', 'SCHEMA').first["TimeZone"]
         @use_insert_returning = @config.key?(:insert_returning) ? self.class.type_cast_config_to_boolean(@config[:insert_returning]) : true
       end
@@ -712,6 +721,10 @@ module ActiveRecord
         !native_database_types[type].nil?
       end
 
+      def update_table_definition(table_name, base) #:nodoc:
+        Table.new(table_name, base)
+      end
+
       protected
 
         # Returns the version of the connected PostgreSQL server.
@@ -738,43 +751,60 @@ module ActiveRecord
 
       private
 
+        def type_map
+          @type_map
+        end
+
         def reload_type_map
-          OID::TYPE_MAP.clear
-          initialize_type_map
+          type_map.clear
+          initialize_type_map(type_map)
+        end
+
+        def add_oid(row, records_by_oid, type_map)
+          return type_map if type_map.key? row['type_elem'].to_i
+
+          if OID.registered_type? row['typname']
+            # this composite type is explicitly registered
+            vector = OID::NAMES[row['typname']]
+          else
+            # use the default for composite types
+            unless type_map.key? row['typelem'].to_i
+              add_oid records_by_oid[row['typelem']], records_by_oid, type_map
+            end
+
+            vector = OID::Vector.new row['typdelim'], type_map[row['typelem'].to_i]
+          end
+
+          type_map[row['oid'].to_i] = vector
+          type_map
         end
 
-        def initialize_type_map
+        def initialize_type_map(type_map)
           result = execute('SELECT oid, typname, typelem, typdelim, typinput FROM pg_type', 'SCHEMA')
           leaves, nodes = result.partition { |row| row['typelem'] == '0' }
 
           # populate the leaf nodes
           leaves.find_all { |row| OID.registered_type? row['typname'] }.each do |row|
-            OID::TYPE_MAP[row['oid'].to_i] = OID::NAMES[row['typname']]
+            type_map[row['oid'].to_i] = OID::NAMES[row['typname']]
           end
 
+          records_by_oid = result.group_by { |row| row['oid'] }
+
           arrays, nodes = nodes.partition { |row| row['typinput'] == 'array_in' }
 
           # populate composite types
-          nodes.find_all { |row| OID::TYPE_MAP.key? row['typelem'].to_i }.each do |row|
-            if OID.registered_type? row['typname']
-              # this composite type is explicitly registered
-              vector = OID::NAMES[row['typname']]
-            else
-              # use the default for composite types
-              vector = OID::Vector.new row['typdelim'], OID::TYPE_MAP[row['typelem'].to_i]
-            end
-
-            OID::TYPE_MAP[row['oid'].to_i] = vector
+          nodes.each do |row|
+            add_oid row, records_by_oid, type_map
           end
 
           # populate array types
-          arrays.find_all { |row| OID::TYPE_MAP.key? row['typelem'].to_i }.each do |row|
-            array = OID::Array.new  OID::TYPE_MAP[row['typelem'].to_i]
-            OID::TYPE_MAP[row['oid'].to_i] = array
+          arrays.find_all { |row| type_map.key? row['typelem'].to_i }.each do |row|
+            array = OID::Array.new  type_map[row['typelem'].to_i]
+            type_map[row['oid'].to_i] = array
           end
         end
 
-        FEATURE_NOT_SUPPORTED = "0A000" # :nodoc:
+        FEATURE_NOT_SUPPORTED = "0A000" #:nodoc:
 
         def exec_no_cache(sql, name, binds)
           log(sql, name, binds) { @connection.async_exec(sql) }
@@ -847,6 +877,12 @@ module ActiveRecord
           PostgreSQLColumn.money_precision = (postgresql_version >= 80300) ? 19 : 10
 
           configure_connection
+        rescue ::PG::Error => error
+          if error.message.include?("does not exist")
+            raise ActiveRecord::NoDatabaseError.new(error.message)
+          else
+            raise error
+          end
         end
 
         # Configures the encoding, verbosity, schema search path, and time zone of the connection.
@@ -951,16 +987,12 @@ module ActiveRecord
         end
 
         def extract_table_ref_from_insert_sql(sql)
-          sql[/into\s+([^\(]*).*values\s*\(/i]
+          sql[/into\s+([^\(]*).*values\s*\(/im]
           $1.strip if $1
         end
 
-        def create_table_definition(name, temporary, options)
-          TableDefinition.new native_database_types, name, temporary, options
-        end
-
-        def update_table_definition(table_name, base)
-          Table.new(table_name, base)
+        def create_table_definition(name, temporary, options, as = nil)
+          TableDefinition.new native_database_types, name, temporary, options, as
         end
     end
   end
diff --git a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
index 2cf1015f2c..92bb70ba53 100644
--- a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
@@ -31,6 +31,12 @@ module ActiveRecord
       db.busy_timeout(ConnectionAdapters::SQLite3Adapter.type_cast_config_to_integer(config[:timeout])) if config[:timeout]
 
       ConnectionAdapters::SQLite3Adapter.new(db, logger, config)
+    rescue Errno::ENOENT => error
+      if error.message.include?("No such file or directory")
+        raise ActiveRecord::NoDatabaseError.new(error.message)
+      else
+        raise error
+      end
     end
   end
 
@@ -586,7 +592,11 @@ module ActiveRecord
 
         def translate_exception(exception, message)
           case exception.message
-          when /column(s)? .* (is|are) not unique/
+          # SQLite 3.8.2 returns a newly formatted error message:
+          #   UNIQUE constraint failed: *table_name*.*column_name*
+          # Older versions of SQLite return:
+          #   column *column_name* is not unique
+          when /column(s)? .* (is|are) not unique/, /UNIQUE constraint failed: .*/
             RecordNotUnique.new(message, exception)
           else
             super