3 files changed, 10 insertions, 7 deletions
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 c7881a6c6c..3e77b92141 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -460,7 +460,6 @@ module ActiveRecord
       # it can be helpful to provide these in a migration's +change+ method so it can be reverted.
       # In that case, +options+ and the block will be used by create_table.
       def drop_table(table_name, options = {})
-        create_table_info_cache.delete(table_name) if create_table_info_cache.key?(table_name)
         execute "DROP#{' TEMPORARY' if options[:temporary]} TABLE#{' IF EXISTS' if options[:if_exists]} #{quote_table_name(table_name)}#{' CASCADE' if options[:force] == :cascade}"
       end
 
@@ -900,12 +899,8 @@ module ActiveRecord
         end
       end
 
-      def create_table_info_cache # :nodoc:
-        @create_table_info_cache ||= {}
-      end
-
       def create_table_info(table_name) # :nodoc:
-        create_table_info_cache[table_name] ||= select_one("SHOW CREATE TABLE #{quote_table_name(table_name)}")["Create Table"]
+        select_one("SHOW CREATE TABLE #{quote_table_name(table_name)}")["Create Table"]
       end
 
       def create_table_definition(*args) # :nodoc:
diff --git a/activerecord/lib/active_record/relation.rb b/activerecord/lib/active_record/relation.rb
index 7a1552856b..93baa882ad 100644
--- a/activerecord/lib/active_record/relation.rb
+++ b/activerecord/lib/active_record/relation.rb
@@ -65,7 +65,7 @@ module ActiveRecord
       @klass.connection.insert(
         im,
         'SQL',
-        primary_key,
+        primary_key || false,
         primary_key_value,
         nil,
         binds)
diff --git a/activerecord/test/cases/primary_keys_test.rb b/activerecord/test/cases/primary_keys_test.rb
index 6c8532cf00..4267ad4a24 100644
--- a/activerecord/test/cases/primary_keys_test.rb
+++ b/activerecord/test/cases/primary_keys_test.rb
@@ -174,6 +174,14 @@ class PrimaryKeysTest < ActiveRecord::TestCase
     assert_equal '2', dashboard.id
   end
 
+  def test_create_without_primary_key_no_extra_query
+    klass = Class.new(ActiveRecord::Base) do
+      self.table_name = 'dashboards'
+    end
+    klass.create! # warmup schema cache
+    assert_queries(3, ignore_none: true) { klass.create! }
+  end
+
   if current_adapter?(:PostgreSQLAdapter)
     def test_serial_with_quoted_sequence_name
       column = MixedCaseMonkey.columns_hash[MixedCaseMonkey.primary_key]