Merge branch 'master' into require_relative_2017

25 files changed, 154 insertions, 98 deletions

diff --git a/activerecord/lib/active_record/associations/collection_association.rb b/activerecord/lib/active_record/associations/collection_association.rb
index bbf3dbb75e..a49fb155ee 100644
--- a/activerecord/lib/active_record/associations/collection_association.rb
+++ b/activerecord/lib/active_record/associations/collection_association.rb
@@ -66,6 +66,7 @@ module ActiveRecord
       def reset
         super
         @target = []
+        @association_ids = nil
       end
 
       def find(*args)
@@ -355,7 +356,10 @@ module ActiveRecord
             transaction do
               add_to_target(build_record(attributes)) do |record|
                 yield(record) if block_given?
-                insert_record(record, true, raise) { @_was_loaded = loaded? }
+                insert_record(record, true, raise) {
+                  @_was_loaded = loaded?
+                  @association_ids = nil
+                }
               end
             end
           end
@@ -428,7 +432,12 @@ module ActiveRecord
           records.each do |record|
             raise_on_type_mismatch!(record)
             add_to_target(record) do
-              result &&= insert_record(record, true, raise) { @_was_loaded = loaded? } unless owner.new_record?
+              unless owner.new_record?
+                result &&= insert_record(record, true, raise) {
+                  @_was_loaded = loaded?
+                  @association_ids = nil
+                }
+              end
             end
           end
 
diff --git a/activerecord/lib/active_record/associations/join_dependency.rb b/activerecord/lib/active_record/associations/join_dependency.rb
index bc66194aef..04cdcb6a7f 100644
--- a/activerecord/lib/active_record/associations/join_dependency.rb
+++ b/activerecord/lib/active_record/associations/join_dependency.rb
@@ -198,8 +198,7 @@ module ActiveRecord
 
         def table_alias_for(reflection, parent, join)
           name = "#{reflection.plural_name}_#{parent.table_name}"
-          name << "_join" if join
-          name
+          join ? "#{name}_join" : name
         end
 
         def walk(left, right)
diff --git a/activerecord/lib/active_record/attribute.rb b/activerecord/lib/active_record/attribute.rb
index 38281158d8..78662433eb 100644
--- a/activerecord/lib/active_record/attribute.rb
+++ b/activerecord/lib/active_record/attribute.rb
@@ -122,7 +122,7 @@ module ActiveRecord
 
     def encode_with(coder)
       coder["name"] = name
-      coder["value_before_type_cast"] = value_before_type_cast if value_before_type_cast
+      coder["value_before_type_cast"] = value_before_type_cast unless value_before_type_cast.nil?
       coder["type"] = type if type
       coder["original_attribute"] = original_attribute if original_attribute
       coder["value"] = value if defined?(@value)
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 61bf5477aa..627b753f01 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
@@ -679,7 +679,7 @@ module ActiveRecord
           # this block can't be easily moved into attempt_to_checkout_all_existing_connections's
           # rescue block, because doing so would put it outside of synchronize section, without
           # being in a critical section thread_report might become inaccurate
-          msg = "could not obtain ownership of all database connections in #{checkout_timeout} seconds"
+          msg = "could not obtain ownership of all database connections in #{checkout_timeout} seconds".dup
 
           thread_report = []
           @connections.each do |conn|
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 af5314c1d6..879626b72a 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb
@@ -51,9 +51,7 @@ module ActiveRecord
 
       # Returns a single value from a record
       def select_value(arel, name = nil, binds = [])
-        if result = select_rows(arel, name, binds).first
-          result.first
-        end
+        single_value_from_rows(select_rows(arel, name, binds))
       end
 
       # Returns an array of the values of the first column in a select:
@@ -68,6 +66,18 @@ module ActiveRecord
         select_all(arel, name, binds).rows
       end
 
+      def query_value(sql, name = nil) # :nodoc:
+        single_value_from_rows(query(sql, name))
+      end
+
+      def query_values(sql, name = nil) # :nodoc:
+        query(sql, name).map(&:first)
+      end
+
+      def query(sql, name = nil) # :nodoc:
+        exec_query(sql, name).rows
+      end
+
       # Executes the SQL statement in the context of this connection and returns
       # the raw result from the connection adapter.
       # Note: depending on your database connector, the result returned by this
@@ -410,7 +420,11 @@ module ActiveRecord
         end
 
         def last_inserted_id(result)
-          row = result.rows.first
+          single_value_from_rows(result.rows)
+        end
+
+        def single_value_from_rows(rows)
+          row = rows.first
           row && row.first
         end
 
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 93f4529202..8865e7c703 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_creation.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_creation.rb
@@ -22,7 +22,7 @@ module ActiveRecord
         private
 
           def visit_AlterTable(o)
-            sql = "ALTER TABLE #{quote_table_name(o.name)} "
+            sql = "ALTER TABLE #{quote_table_name(o.name)} ".dup
             sql << o.adds.map { |col| accept col }.join(" ")
             sql << o.foreign_key_adds.map { |fk| visit_AddForeignKey fk }.join(" ")
             sql << o.foreign_key_drops.map { |fk| visit_DropForeignKey fk }.join(" ")
@@ -30,17 +30,17 @@ module ActiveRecord
 
           def visit_ColumnDefinition(o)
             o.sql_type = type_to_sql(o.type, o.options)
-            column_sql = "#{quote_column_name(o.name)} #{o.sql_type}"
+            column_sql = "#{quote_column_name(o.name)} #{o.sql_type}".dup
             add_column_options!(column_sql, column_options(o)) unless o.type == :primary_key
             column_sql
           end
 
           def visit_AddColumnDefinition(o)
-            "ADD #{accept(o.column)}"
+            "ADD #{accept(o.column)}".dup
           end
 
           def visit_TableDefinition(o)
-            create_sql = "CREATE#{' TEMPORARY' if o.temporary} TABLE #{quote_table_name(o.name)} "
+            create_sql = "CREATE#{' TEMPORARY' if o.temporary} TABLE #{quote_table_name(o.name)} ".dup
 
             statements = o.columns.map { |c| accept c }
             statements << accept(o.primary_keys) if o.primary_keys
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 7633f52a83..475463c4fd 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
@@ -31,7 +31,7 @@ module ActiveRecord
       # Returns the relation names useable to back Active Record models.
       # For most adapters this means all #tables and #views.
       def data_sources
-        select_values(data_source_sql, "SCHEMA")
+        query_values(data_source_sql, "SCHEMA")
       rescue NotImplementedError
         tables | views
       end
@@ -41,14 +41,14 @@ module ActiveRecord
       #   data_source_exists?(:ebooks)
       #
       def data_source_exists?(name)
-        select_values(data_source_sql(name), "SCHEMA").any? if name.present?
+        query_values(data_source_sql(name), "SCHEMA").any? if name.present?
       rescue NotImplementedError
         data_sources.include?(name.to_s)
       end
 
       # Returns an array of table names defined in the database.
       def tables
-        select_values(data_source_sql(type: "BASE TABLE"), "SCHEMA")
+        query_values(data_source_sql(type: "BASE TABLE"), "SCHEMA")
       end
 
       # Checks to see if the table +table_name+ exists on the database.
@@ -56,14 +56,14 @@ module ActiveRecord
       #   table_exists?(:developers)
       #
       def table_exists?(table_name)
-        select_values(data_source_sql(table_name, type: "BASE TABLE"), "SCHEMA").any? if table_name.present?
+        query_values(data_source_sql(table_name, type: "BASE TABLE"), "SCHEMA").any? if table_name.present?
       rescue NotImplementedError
         tables.include?(table_name.to_s)
       end
 
       # Returns an array of view names defined in the database.
       def views
-        select_values(data_source_sql(type: "VIEW"), "SCHEMA")
+        query_values(data_source_sql(type: "VIEW"), "SCHEMA")
       end
 
       # Checks to see if the view +view_name+ exists on the database.
@@ -71,7 +71,7 @@ module ActiveRecord
       #   view_exists?(:ebooks)
       #
       def view_exists?(view_name)
-        select_values(data_source_sql(view_name, type: "VIEW"), "SCHEMA").any? if view_name.present?
+        query_values(data_source_sql(view_name, type: "VIEW"), "SCHEMA").any? if view_name.present?
       rescue NotImplementedError
         views.include?(view_name.to_s)
       end
@@ -1348,7 +1348,7 @@ module ActiveRecord
           sm_table = quote_table_name(ActiveRecord::SchemaMigration.table_name)
 
           if versions.is_a?(Array)
-            sql = "INSERT INTO #{sm_table} (version) VALUES\n"
+            sql = "INSERT INTO #{sm_table} (version) VALUES\n".dup
             sql << versions.map { |v| "(#{quote(v)})" }.join(",\n")
             sql << ";\n\n"
             sql
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/transaction.rb b/activerecord/lib/active_record/connection_adapters/abstract/transaction.rb
index 19b7821494..f63d09039f 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/transaction.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/transaction.rb
@@ -1,10 +1,13 @@
 module ActiveRecord
   module ConnectionAdapters
     class TransactionState
-      VALID_STATES = Set.new([:committed, :rolledback, nil])
-
       def initialize(state = nil)
         @state = state
+        @children = []
+      end
+
+      def add_child(state)
+        @children << state
       end
 
       def finalized?
@@ -19,15 +22,43 @@ module ActiveRecord
         @state == :rolledback
       end
 
+      def fully_completed?
+        completed?
+      end
+
       def completed?
         committed? || rolledback?
       end
 
       def set_state(state)
-        unless VALID_STATES.include?(state)
+        ActiveSupport::Deprecation.warn(<<-MSG.squish)
+          The set_state method is deprecated and will be removed in
+          Rails 6.0. Please use rollback! or commit! to set transaction
+          state directly.
+        MSG
+        case state
+        when :rolledback
+          rollback!
+        when :committed
+          commit!
+        when nil
+          nullify!
+        else
           raise ArgumentError, "Invalid transaction state: #{state}"
         end
-        @state = state
+      end
+
+      def rollback!
+        @children.each { |c| c.rollback! }
+        @state = :rolledback
+      end
+
+      def commit!
+        @state = :committed
+      end
+
+      def nullify!
+        @state = nil
       end
     end
 
@@ -57,7 +88,7 @@ module ActiveRecord
       end
 
       def rollback
-        @state.set_state(:rolledback)
+        @state.rollback!
       end
 
       def rollback_records
@@ -72,7 +103,7 @@ module ActiveRecord
       end
 
       def commit
-        @state.set_state(:committed)
+        @state.commit!
       end
 
       def before_commit_records
@@ -100,8 +131,11 @@ module ActiveRecord
     end
 
     class SavepointTransaction < Transaction
-      def initialize(connection, savepoint_name, options, *args)
+      def initialize(connection, savepoint_name, parent_transaction, options, *args)
         super(connection, options, *args)
+
+        parent_transaction.state.add_child(@state)
+
         if options[:isolation]
           raise ActiveRecord::TransactionIsolationError, "cannot set transaction isolation in a nested transaction"
         end
@@ -155,7 +189,7 @@ module ActiveRecord
             if @stack.empty?
               RealTransaction.new(@connection, options, run_commit_callbacks: run_commit_callbacks)
             else
-              SavepointTransaction.new(@connection, "active_record_#{@stack.size}", options,
+              SavepointTransaction.new(@connection, "active_record_#{@stack.size}", @stack.last, options,
                                        run_commit_callbacks: run_commit_callbacks)
             end
 
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
index 8f1506befa..cfe1892d78 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
@@ -147,7 +147,7 @@ module ActiveRecord
       # this method must only be called while holding connection pool's mutex
       def lease
         if in_use?
-          msg = "Cannot lease connection, "
+          msg = "Cannot lease connection, ".dup
           if @owner == Thread.current
             msg << "it is already leased by the current thread."
           else
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 5cec970dca..caa125576c 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -120,11 +120,11 @@ module ActiveRecord
       end
 
       def get_advisory_lock(lock_name, timeout = 0) # :nodoc:
-        select_value("SELECT GET_LOCK(#{quote(lock_name)}, #{timeout})") == 1
+        query_value("SELECT GET_LOCK(#{quote(lock_name)}, #{timeout})") == 1
       end
 
       def release_advisory_lock(lock_name) # :nodoc:
-        select_value("SELECT RELEASE_LOCK(#{quote(lock_name)})") == 1
+        query_value("SELECT RELEASE_LOCK(#{quote(lock_name)})") == 1
       end
 
       def native_database_types
@@ -132,7 +132,7 @@ module ActiveRecord
       end
 
       def index_algorithms
-        { default: "ALGORITHM = DEFAULT", copy: "ALGORITHM = COPY", inplace: "ALGORITHM = INPLACE" }
+        { default: "ALGORITHM = DEFAULT".dup, copy: "ALGORITHM = COPY".dup, inplace: "ALGORITHM = INPLACE".dup }
       end
 
       # HELPER METHODS ===========================================
@@ -152,7 +152,7 @@ module ActiveRecord
       # REFERENTIAL INTEGRITY ====================================
 
       def disable_referential_integrity #:nodoc:
-        old = select_value("SELECT @@FOREIGN_KEY_CHECKS")
+        old = query_value("SELECT @@FOREIGN_KEY_CHECKS")
 
         begin
           update("SET FOREIGN_KEY_CHECKS = 0")
@@ -267,7 +267,7 @@ module ActiveRecord
       end
 
       def current_database
-        select_value "SELECT DATABASE() as db"
+        query_value("SELECT database()", "SCHEMA")
       end
 
       # Returns the database character set.
@@ -287,7 +287,7 @@ module ActiveRecord
       def table_comment(table_name) # :nodoc:
         scope = quoted_scope(table_name)
 
-        select_value(<<-SQL.strip_heredoc, "SCHEMA")
+        query_value(<<-SQL.strip_heredoc, "SCHEMA")
           SELECT table_comment
           FROM information_schema.tables
           WHERE table_schema = #{scope[:schema]}
@@ -379,7 +379,7 @@ module ActiveRecord
 
       def add_index(table_name, column_name, options = {}) #:nodoc:
         index_name, index_type, index_columns, _, index_algorithm, index_using, comment = add_index_options(table_name, column_name, options)
-        sql = "CREATE #{index_type} INDEX #{quote_column_name(index_name)} #{index_using} ON #{quote_table_name(table_name)} (#{index_columns}) #{index_algorithm}"
+        sql = "CREATE #{index_type} INDEX #{quote_column_name(index_name)} #{index_using} ON #{quote_table_name(table_name)} (#{index_columns}) #{index_algorithm}".dup
         execute add_sql_comment!(sql, comment)
       end
 
@@ -393,7 +393,7 @@ module ActiveRecord
 
         scope = quoted_scope(table_name)
 
-        fk_info = select_all(<<-SQL.strip_heredoc, "SCHEMA")
+        fk_info = exec_query(<<-SQL.strip_heredoc, "SCHEMA")
           SELECT fk.referenced_table_name AS 'to_table',
                  fk.referenced_column_name AS 'primary_key',
                  fk.column_name AS 'column',
@@ -464,13 +464,13 @@ module ActiveRecord
             super
           end
 
-        sql << " unsigned" if unsigned && type != :primary_key
+        sql = "#{sql} unsigned" if unsigned && type != :primary_key
         sql
       end
 
       # SHOW VARIABLES LIKE 'name'
       def show_variable(name)
-        select_value("SELECT @@#{name}", "SCHEMA")
+        query_value("SELECT @@#{name}", "SCHEMA")
       rescue ActiveRecord::StatementInvalid
         nil
       end
@@ -480,7 +480,7 @@ module ActiveRecord
 
         scope = quoted_scope(table_name)
 
-        select_values(<<-SQL.strip_heredoc, "SCHEMA")
+        query_values(<<-SQL.strip_heredoc, "SCHEMA")
           SELECT column_name
           FROM information_schema.key_column_usage
           WHERE constraint_name = 'PRIMARY'
@@ -694,7 +694,7 @@ module ActiveRecord
             auto_increment: column.auto_increment?
           }
 
-          current_type = select_one("SHOW COLUMNS FROM #{quote_table_name(table_name)} LIKE #{quote(column_name)}", "SCHEMA")["Type"]
+          current_type = exec_query("SHOW COLUMNS FROM #{quote_table_name(table_name)} LIKE #{quote(column_name)}", "SCHEMA").first["Type"]
           td = create_table_definition(table_name)
           cd = td.new_column_definition(new_column_name, current_type, options)
           schema_creation.accept(ChangeColumnDefinition.new(cd, column.name))
@@ -778,7 +778,7 @@ module ActiveRecord
           # http://dev.mysql.com/doc/refman/5.7/en/set-statement.html#id944430
           # (trailing comma because variable_assignments will always have content)
           if @config[:encoding]
-            encoding = "NAMES #{@config[:encoding]}"
+            encoding = "NAMES #{@config[:encoding]}".dup
             encoding << " COLLATE #{@config[:collation]}" if @config[:collation]
             encoding << ", "
           end
@@ -804,7 +804,7 @@ module ActiveRecord
         end
 
         def create_table_info(table_name) # :nodoc:
-          select_one("SHOW CREATE TABLE #{quote_table_name(table_name)}")["Create Table"]
+          exec_query("SHOW CREATE TABLE #{quote_table_name(table_name)}", "SCHEMA").first["Create Table"]
         end
 
         def arel_visitor
diff --git a/activerecord/lib/active_record/connection_adapters/mysql/database_statements.rb b/activerecord/lib/active_record/connection_adapters/mysql/database_statements.rb
index 9f1021456b..bda482a00f 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql/database_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql/database_statements.rb
@@ -13,6 +13,10 @@ module ActiveRecord
           result
         end
 
+        def query(sql, name = nil) # :nodoc:
+          execute(sql, name).to_a
+        end
+
         # Executes the SQL statement in the context of this connection.
         def execute(sql, name = nil)
           # make sure we carry over any changes to ActiveRecord::Base.default_timezone that have been
diff --git a/activerecord/lib/active_record/connection_adapters/mysql/schema_creation.rb b/activerecord/lib/active_record/connection_adapters/mysql/schema_creation.rb
index 083cd6340f..eea4984680 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql/schema_creation.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql/schema_creation.rb
@@ -16,7 +16,7 @@ module ActiveRecord
           end
 
           def visit_ChangeColumnDefinition(o)
-            change_column_sql = "CHANGE #{quote_column_name(o.name)} #{accept(o.column)}"
+            change_column_sql = "CHANGE #{quote_column_name(o.name)} #{accept(o.column)}".dup
             add_column_position!(change_column_sql, column_options(o.column))
           end
 
@@ -63,7 +63,7 @@ module ActiveRecord
 
           def index_in_create(table_name, column_name, options)
             index_name, index_type, index_columns, _, _, index_using, comment = @conn.add_index_options(table_name, column_name, options)
-            add_sql_comment!("#{index_type} INDEX #{quote_column_name(index_name)} #{index_using} (#{index_columns})", comment)
+            add_sql_comment!("#{index_type} INDEX #{quote_column_name(index_name)} #{index_using} (#{index_columns})".dup, comment)
           end
       end
     end
diff --git a/activerecord/lib/active_record/connection_adapters/mysql/schema_dumper.rb b/activerecord/lib/active_record/connection_adapters/mysql/schema_dumper.rb
index f21b2546de..eff96e329f 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql/schema_dumper.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql/schema_dumper.rb
@@ -47,7 +47,7 @@ module ActiveRecord
           def schema_collation(column)
             if column.collation && table_name = column.table_name
               @table_collation_cache ||= {}
-              @table_collation_cache[table_name] ||= select_one("SHOW TABLE STATUS LIKE #{quote(table_name)}")["Collation"]
+              @table_collation_cache[table_name] ||= exec_query("SHOW TABLE STATUS LIKE #{quote(table_name)}", "SCHEMA").first["Collation"]
               column.collation.inspect if column.collation != @table_collation_cache[table_name]
             end
           end
@@ -64,7 +64,7 @@ module ActiveRecord
                     " WHERE table_schema = #{scope[:schema]}" \
                     "   AND table_name = #{scope[:name]}" \
                     "   AND column_name = #{quote(column.name)}"
-              select_value(sql, "SCHEMA").inspect
+              query_value(sql, "SCHEMA").inspect
             end
           end
       end
diff --git a/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb
index fc57e41fc9..a01fbba201 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb
@@ -102,7 +102,7 @@ module ActiveRecord
           def data_source_sql(name = nil, type: nil)
             scope = quoted_scope(name, type: type)
 
-            sql = "SELECT table_name FROM information_schema.tables"
+            sql = "SELECT table_name FROM information_schema.tables".dup
             sql << " WHERE table_schema = #{scope[:schema]}"
             sql << " AND table_name = #{scope[:name]}" if scope[:name]
             sql << " AND table_type = #{scope[:type]}" if scope[:type]
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb b/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb
index 44eb666965..ee4230c6f2 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb
@@ -78,7 +78,7 @@ module ActiveRecord
 
         private
           def lookup_cast_type(sql_type)
-            super(select_value("SELECT #{quote(sql_type)}::regtype::oid", "SCHEMA").to_i)
+            super(query_value("SELECT #{quote(sql_type)}::regtype::oid", "SCHEMA").to_i)
           end
 
           def _quote(value)
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 7aa034f901..a710ea6cc9 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
@@ -60,7 +60,7 @@ module ActiveRecord
 
         # Returns true if schema exists.
         def schema_exists?(name)
-          select_value("SELECT COUNT(*) FROM pg_namespace WHERE nspname = #{quote(name)}", "SCHEMA").to_i > 0
+          query_value("SELECT COUNT(*) FROM pg_namespace WHERE nspname = #{quote(name)}", "SCHEMA").to_i > 0
         end
 
         # Verifies existence of an index with a given name.
@@ -73,7 +73,7 @@ module ActiveRecord
           table = quoted_scope(table_name)
           index = quoted_scope(index_name)
 
-          select_value(<<-SQL, "SCHEMA").to_i > 0
+          query_value(<<-SQL, "SCHEMA").to_i > 0
             SELECT COUNT(*)
             FROM pg_class t
             INNER JOIN pg_index d ON t.oid = d.indrelid
@@ -163,7 +163,7 @@ module ActiveRecord
         def table_comment(table_name) # :nodoc:
           scope = quoted_scope(table_name, type: "BASE TABLE")
           if scope[:name]
-            select_value(<<-SQL.strip_heredoc, "SCHEMA")
+            query_value(<<-SQL.strip_heredoc, "SCHEMA")
               SELECT pg_catalog.obj_description(c.oid, 'pg_class')
               FROM pg_catalog.pg_class c
                 LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
@@ -176,32 +176,32 @@ module ActiveRecord
 
         # Returns the current database name.
         def current_database
-          select_value("SELECT current_database()", "SCHEMA")
+          query_value("SELECT current_database()", "SCHEMA")
         end
 
         # Returns the current schema name.
         def current_schema
-          select_value("SELECT current_schema", "SCHEMA")
+          query_value("SELECT current_schema", "SCHEMA")
         end
 
         # Returns the current database encoding format.
         def encoding
-          select_value("SELECT pg_encoding_to_char(encoding) FROM pg_database WHERE datname = current_database()", "SCHEMA")
+          query_value("SELECT pg_encoding_to_char(encoding) FROM pg_database WHERE datname = current_database()", "SCHEMA")
         end
 
         # Returns the current database collation.
         def collation
-          select_value("SELECT datcollate FROM pg_database WHERE datname = current_database()", "SCHEMA")
+          query_value("SELECT datcollate FROM pg_database WHERE datname = current_database()", "SCHEMA")
         end
 
         # Returns the current database ctype.
         def ctype
-          select_value("SELECT datctype FROM pg_database WHERE datname = current_database()", "SCHEMA")
+          query_value("SELECT datctype FROM pg_database WHERE datname = current_database()", "SCHEMA")
         end
 
         # Returns an array of schema names.
         def schema_names
-          select_values(<<-SQL, "SCHEMA")
+          query_values(<<-SQL, "SCHEMA")
             SELECT nspname
               FROM pg_namespace
              WHERE nspname !~ '^pg_.*'
@@ -234,12 +234,12 @@ module ActiveRecord
 
         # Returns the active schema search path.
         def schema_search_path
-          @schema_search_path ||= select_value("SHOW search_path", "SCHEMA")
+          @schema_search_path ||= query_value("SHOW search_path", "SCHEMA")
         end
 
         # Returns the current client message level.
         def client_min_messages
-          select_value("SHOW client_min_messages", "SCHEMA")
+          query_value("SHOW client_min_messages", "SCHEMA")
         end
 
         # Set the client message level.
@@ -257,7 +257,7 @@ module ActiveRecord
         end
 
         def serial_sequence(table, column)
-          select_value("SELECT pg_get_serial_sequence(#{quote(table)}, #{quote(column)})", "SCHEMA")
+          query_value("SELECT pg_get_serial_sequence(#{quote(table)}, #{quote(column)})", "SCHEMA")
         end
 
         # Sets the sequence of a table's primary key to the specified value.
@@ -268,7 +268,7 @@ module ActiveRecord
             if sequence
               quoted_sequence = quote_table_name(sequence)
 
-              select_value("SELECT setval(#{quote(quoted_sequence)}, #{value})", "SCHEMA")
+              query_value("SELECT setval(#{quote(quoted_sequence)}, #{value})", "SCHEMA")
             else
               @logger.warn "#{table} has primary key #{pk} with no default sequence." if @logger
             end
@@ -290,18 +290,16 @@ module ActiveRecord
 
           if pk && sequence
             quoted_sequence = quote_table_name(sequence)
-            max_pk = select_value("select MAX(#{quote_column_name pk}) from #{quote_table_name(table)}")
+            max_pk = query_value("SELECT MAX(#{quote_column_name pk}) FROM #{quote_table_name(table)}", "SCHEMA")
             if max_pk.nil?
               if postgresql_version >= 100000
-                minvalue = select_value("SELECT seqmin from pg_sequence where seqrelid = #{quote(quoted_sequence)}::regclass")
+                minvalue = query_value("SELECT seqmin FROM pg_sequence WHERE seqrelid = #{quote(quoted_sequence)}::regclass", "SCHEMA")
               else
-                minvalue = select_value("SELECT min_value FROM #{quoted_sequence}")
+                minvalue = query_value("SELECT min_value FROM #{quoted_sequence}", "SCHEMA")
               end
             end
 
-            select_value(<<-end_sql, "SCHEMA")
-              SELECT setval(#{quote(quoted_sequence)}, #{max_pk ? max_pk : minvalue}, #{max_pk ? true : false})
-            end_sql
+            query_value("SELECT setval(#{quote(quoted_sequence)}, #{max_pk ? max_pk : minvalue}, #{max_pk ? true : false})", "SCHEMA")
           end
         end
 
@@ -360,7 +358,7 @@ module ActiveRecord
         end
 
         def primary_keys(table_name) # :nodoc:
-          select_values(<<-SQL.strip_heredoc, "SCHEMA")
+          query_values(<<-SQL.strip_heredoc, "SCHEMA")
             SELECT a.attname
               FROM (
                      SELECT indrelid, indkey, generate_subscripts(indkey, 1) idx
@@ -408,7 +406,7 @@ module ActiveRecord
           quoted_table_name = quote_table_name(table_name)
           quoted_column_name = quote_column_name(column_name)
           sql_type = type_to_sql(type, options)
-          sql = "ALTER TABLE #{quoted_table_name} ALTER COLUMN #{quoted_column_name} TYPE #{sql_type}"
+          sql = "ALTER TABLE #{quoted_table_name} ALTER COLUMN #{quoted_column_name} TYPE #{sql_type}".dup
           if options[:collation]
             sql << " COLLATE \"#{options[:collation]}\""
           end
@@ -511,7 +509,7 @@ module ActiveRecord
 
         def foreign_keys(table_name)
           scope = quoted_scope(table_name)
-          fk_info = select_all(<<-SQL.strip_heredoc, "SCHEMA")
+          fk_info = exec_query(<<-SQL.strip_heredoc, "SCHEMA")
             SELECT t2.oid::regclass::text AS to_table, a1.attname AS column, a2.attname AS primary_key, c.conname AS name, c.confupdtype AS on_update, c.confdeltype AS on_delete
             FROM pg_constraint c
             JOIN pg_class t1 ON c.conrelid = t1.oid
@@ -568,7 +566,7 @@ module ActiveRecord
               super
             end
 
-          sql << "[]" if array && type != :primary_key
+          sql = "#{sql}[]" if array && type != :primary_key
           sql
         end
 
@@ -637,7 +635,7 @@ module ActiveRecord
             scope = quoted_scope(name, type: type)
             scope[:type] ||= "'r','v','m'" # (r)elation/table, (v)iew, (m)aterialized view
 
-            sql = "SELECT c.relname FROM pg_class c LEFT JOIN pg_namespace n ON n.oid = c.relnamespace"
+            sql = "SELECT c.relname FROM pg_class c LEFT JOIN pg_namespace n ON n.oid = c.relnamespace".dup
             sql << " WHERE n.nspname = #{scope[:schema]}"
             sql << " AND c.relname = #{scope[:name]}" if scope[:name]
             sql << " AND c.relkind IN (#{scope[:type]})"
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
index 455f9b9be3..8baef19030 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
@@ -312,14 +312,14 @@ module ActiveRecord
         unless lock_id.is_a?(Integer) && lock_id.bit_length <= 63
           raise(ArgumentError, "Postgres requires advisory lock ids to be a signed 64 bit integer")
         end
-        select_value("SELECT pg_try_advisory_lock(#{lock_id});")
+        query_value("SELECT pg_try_advisory_lock(#{lock_id})")
       end
 
       def release_advisory_lock(lock_id) # :nodoc:
         unless lock_id.is_a?(Integer) && lock_id.bit_length <= 63
           raise(ArgumentError, "Postgres requires advisory lock ids to be a signed 64 bit integer")
         end
-        select_value("SELECT pg_advisory_unlock(#{lock_id})")
+        query_value("SELECT pg_advisory_unlock(#{lock_id})")
       end
 
       def enable_extension(name)
@@ -336,15 +336,14 @@ module ActiveRecord
 
       def extension_enabled?(name)
         if supports_extensions?
-          res = exec_query "SELECT EXISTS(SELECT * FROM pg_available_extensions WHERE name = '#{name}' AND installed_version IS NOT NULL) as enabled",
-            "SCHEMA"
+          res = exec_query("SELECT EXISTS(SELECT * FROM pg_available_extensions WHERE name = '#{name}' AND installed_version IS NOT NULL) as enabled", "SCHEMA")
           res.cast_values.first
         end
       end
 
       def extensions
         if supports_extensions?
-          exec_query("SELECT extname from pg_extension", "SCHEMA").cast_values
+          exec_query("SELECT extname FROM pg_extension", "SCHEMA").cast_values
         else
           super
         end
@@ -352,14 +351,14 @@ module ActiveRecord
 
       # Returns the configured supported identifier length supported by PostgreSQL
       def table_alias_length
-        @max_identifier_length ||= select_value("SHOW max_identifier_length", "SCHEMA").to_i
+        @max_identifier_length ||= query_value("SHOW max_identifier_length", "SCHEMA").to_i
       end
       alias index_name_length table_alias_length
 
       # Set the authorized user for this session
       def session_auth=(user)
         clear_cache!
-        exec_query "SET SESSION AUTHORIZATION #{user}"
+        execute("SET SESSION AUTHORIZATION #{user}")
       end
 
       def use_insert_returning?
diff --git a/activerecord/lib/active_record/connection_adapters/sqlite3/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/sqlite3/schema_statements.rb
index e02491edb6..31e83f9260 100644
--- a/activerecord/lib/active_record/connection_adapters/sqlite3/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/sqlite3/schema_statements.rb
@@ -11,7 +11,7 @@ module ActiveRecord
           end
 
           exec_query("PRAGMA index_list(#{quote_table_name(table_name)})", "SCHEMA").map do |row|
-            index_sql = select_value(<<-SQL, "SCHEMA")
+            index_sql = query_value(<<-SQL, "SCHEMA")
               SELECT sql
               FROM sqlite_master
               WHERE name = #{quote(row['name'])} AND type = 'index'
@@ -67,7 +67,7 @@ module ActiveRecord
             scope = quoted_scope(name, type: type)
             scope[:type] ||= "'table','view'"
 
-            sql = "SELECT name FROM sqlite_master WHERE name <> 'sqlite_sequence'"
+            sql = "SELECT name FROM sqlite_master WHERE name <> 'sqlite_sequence'".dup
             sql << " AND name = #{scope[:name]}" if scope[:name]
             sql << " AND type IN (#{scope[:type]})"
             sql
diff --git a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
index 0b38aa45f7..04129841e4 100644
--- a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
@@ -169,7 +169,7 @@ module ActiveRecord
       # REFERENTIAL INTEGRITY ====================================
 
       def disable_referential_integrity # :nodoc:
-        old = select_value("PRAGMA foreign_keys")
+        old = query_value("PRAGMA foreign_keys")
 
         begin
           execute("PRAGMA foreign_keys = OFF")
@@ -337,7 +337,7 @@ module ActiveRecord
       alias :add_belongs_to :add_reference
 
       def foreign_keys(table_name)
-        fk_info = select_all("PRAGMA foreign_key_list(#{quote(table_name)})", "SCHEMA")
+        fk_info = exec_query("PRAGMA foreign_key_list(#{quote(table_name)})", "SCHEMA")
         fk_info.map do |row|
           options = {
             column: row["from"],
@@ -443,7 +443,7 @@ module ActiveRecord
         end
 
         def sqlite_version
-          @sqlite_version ||= SQLite3Adapter::Version.new(select_value("SELECT sqlite_version(*)"))
+          @sqlite_version ||= SQLite3Adapter::Version.new(query_value("SELECT sqlite_version(*)"))
         end
 
         def translate_exception(exception, message)
diff --git a/activerecord/lib/active_record/explain.rb b/activerecord/lib/active_record/explain.rb
index 78cbe7b2dd..eff5990f3a 100644
--- a/activerecord/lib/active_record/explain.rb
+++ b/activerecord/lib/active_record/explain.rb
@@ -16,7 +16,7 @@ module ActiveRecord
     # Returns a formatted string ready to be logged.
     def exec_explain(queries) # :nodoc:
       str = queries.map do |sql, binds|
-        msg = "EXPLAIN for: #{sql}"
+        msg = "EXPLAIN for: #{sql}".dup
         unless binds.empty?
           msg << " "
           msg << binds.map { |attr| render_bind(attr) }.inspect
diff --git a/activerecord/lib/active_record/migration.rb b/activerecord/lib/active_record/migration.rb
index 51c82f4ced..1ff1dcad43 100644
--- a/activerecord/lib/active_record/migration.rb
+++ b/activerecord/lib/active_record/migration.rb
@@ -157,7 +157,7 @@ module ActiveRecord
 
   class ProtectedEnvironmentError < ActiveRecordError #:nodoc:
     def initialize(env = "production")
-      msg = "You are attempting to run a destructive action against your '#{env}' database.\n"
+      msg = "You are attempting to run a destructive action against your '#{env}' database.\n".dup
       msg << "If you are sure you want to continue, run the same command with the environment variable:\n"
       msg << "DISABLE_DATABASE_ENVIRONMENT_CHECK=1"
       super(msg)
@@ -166,7 +166,7 @@ module ActiveRecord
 
   class EnvironmentMismatchError < ActiveRecordError
     def initialize(current: nil, stored: nil)
-      msg =  "You are attempting to modify a database that was last run in `#{ stored }` environment.\n"
+      msg =  "You are attempting to modify a database that was last run in `#{ stored }` environment.\n".dup
       msg << "You are running in `#{ current }` environment. "
       msg << "If you are sure you want to continue, first set the environment using:\n\n"
       msg << "        bin/rails db:environment:set"
@@ -1239,7 +1239,7 @@ module ActiveRecord
           record_version_state_after_migrating(migration.version)
         end
       rescue => e
-        msg = "An error has occurred, "
+        msg = "An error has occurred, ".dup
         msg << "this and " if use_transaction?(migration)
         msg << "all later migrations canceled:\n\n#{e}"
         raise StandardError, msg, e.backtrace
diff --git a/activerecord/lib/active_record/reflection.rb b/activerecord/lib/active_record/reflection.rb
index 73761ed7ed..8ff2f50fdb 100644
--- a/activerecord/lib/active_record/reflection.rb
+++ b/activerecord/lib/active_record/reflection.rb
@@ -592,7 +592,7 @@ module ActiveRecord
       end
 
       VALID_AUTOMATIC_INVERSE_MACROS = [:has_many, :has_one, :belongs_to]
-      INVALID_AUTOMATIC_INVERSE_OPTIONS = [:conditions, :through, :polymorphic, :foreign_key]
+      INVALID_AUTOMATIC_INVERSE_OPTIONS = [:conditions, :through, :foreign_key]
 
       def add_as_source(seed)
         seed
@@ -663,9 +663,8 @@ module ActiveRecord
         # us from being able to guess the inverse automatically. First, the
         # <tt>inverse_of</tt> option cannot be set to false. Second, we must
         # have <tt>has_many</tt>, <tt>has_one</tt>, <tt>belongs_to</tt> associations.
-        # Third, we must not have options such as <tt>:polymorphic</tt> or
-        # <tt>:foreign_key</tt> which prevent us from correctly guessing the
-        # inverse association.
+        # Third, we must not have options such as <tt>:foreign_key</tt>
+        # which prevent us from correctly guessing the inverse association.
         #
         # Anything with a scope can additionally ruin our attempt at finding an
         # inverse, so we exclude reflections with scopes.
diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb
index df8909379f..eee0f36f63 100644
--- a/activerecord/lib/active_record/relation/finder_methods.rb
+++ b/activerecord/lib/active_record/relation/finder_methods.rb
@@ -334,14 +334,14 @@ module ActiveRecord
       name = @klass.name
 
       if ids.nil?
-        error = "Couldn't find #{name}"
+        error = "Couldn't find #{name}".dup
         error << " with#{conditions}" if conditions
         raise RecordNotFound.new(error, name)
       elsif Array(ids).size == 1
         error = "Couldn't find #{name} with '#{key}'=#{ids}#{conditions}"
         raise RecordNotFound.new(error, name, key, ids)
       else
-        error = "Couldn't find all #{name.pluralize} with '#{key}': "
+        error = "Couldn't find all #{name.pluralize} with '#{key}': ".dup
         error << "(#{ids.join(", ")})#{conditions} (found #{result_size} results, but was looking for #{expected_size})"
 
         raise RecordNotFound.new(error, name, primary_key, ids)
diff --git a/activerecord/lib/active_record/tasks/mysql_database_tasks.rb b/activerecord/lib/active_record/tasks/mysql_database_tasks.rb
index 47e13d09d8..ff6745f7b5 100644
--- a/activerecord/lib/active_record/tasks/mysql_database_tasks.rb
+++ b/activerecord/lib/active_record/tasks/mysql_database_tasks.rb
@@ -151,7 +151,7 @@ IDENTIFIED BY '#{configuration['password']}' WITH GRANT OPTION;
         end
 
         def run_cmd_error(cmd, args, action)
-          msg = "failed to execute: `#{cmd}`\n"
+          msg = "failed to execute: `#{cmd}`\n".dup
           msg << "Please check the output above for any errors and make sure that `#{cmd}` is installed in your PATH and has proper permissions.\n\n"
           msg
         end
diff --git a/activerecord/lib/active_record/transactions.rb b/activerecord/lib/active_record/transactions.rb
index 45795fa287..463bb1f314 100644
--- a/activerecord/lib/active_record/transactions.rb
+++ b/activerecord/lib/active_record/transactions.rb
@@ -490,7 +490,7 @@ module ActiveRecord
       def update_attributes_from_transaction_state(transaction_state)
         if transaction_state && transaction_state.finalized?
           restore_transaction_record_state if transaction_state.rolledback?
-          clear_transaction_record_state
+          clear_transaction_record_state if transaction_state.fully_completed?
         end
       end
   end