2 files changed, 3 insertions, 6 deletions
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 6981ea6ecd..9f0335b31d 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
@@ -966,7 +966,7 @@ module ActiveRecord
       # [<tt>:on_update</tt>]
       #   Action that happens <tt>ON UPDATE</tt>. Valid values are +:nullify+, +:cascade+ and +:restrict+
       # [<tt>:validate</tt>]
-      #   (Postgres only) Specify whether or not the constraint should be validated. Defaults to +true+.
+      #   (PostgreSQL only) Specify whether or not the constraint should be validated. Defaults to +true+.
       def add_foreign_key(from_table, to_table, options = {})
         return unless supports_foreign_keys?
 
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 1199c0ad1b..a14394fe04 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql/database_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql/database_statements.rb
@@ -145,15 +145,12 @@ module ActiveRecord
             elsif previous_packet.nil?
               true
             else
-              (current_packet.bytesize + previous_packet.bytesize) > max_allowed_packet
+              (current_packet.bytesize + previous_packet.bytesize + 2) > max_allowed_packet
             end
           end
 
           def max_allowed_packet
-            @max_allowed_packet ||= begin
-              bytes_margin = 2
-              show_variable("max_allowed_packet") - bytes_margin
-            end
+            @max_allowed_packet ||= show_variable("max_allowed_packet")
           end
 
           def exec_stmt_and_free(sql, name, binds, cache_stmt: false)