Shadow Table

Its a known problem that changing the Storage Engine from MyISAM to InnoDB can cause some problems
[ 1
] if you have queries of this type:

SELECT COUNT(*) from table;

Luckily this query happens rarely and if, the query can be easily omitted or worked around by guesstimating the amount of rows in the table. For example with:

SHOW TABLE STATUS LIKE 'test';

But in some rare cases customer really needs these values for some reasons. To not exhaust the resources of the server with this query which can be fired …

CREATE TABLE `order` (
  id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY
, name VARCHAR(64) NOT NULL
) ENGINE = InnoDB;

INSERT INTO `order` VALUES
  (NULL, 'Test order 1')
, (NULL, 'Test order 2')
, (NULL, 'Test order 3');


CREATE TABLE pos (
  id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY
, order_id INT UNSIGNED NOT NULL
, name VARCHAR(64) NOT NULL
, amount SMALLINT NOT NULL
, price DECIMAL (6,2) NOT NULL
, status TINYINT NULL
) ENGINE = InnoDB;

INSERT INTO pos VALUES
  (null, 1, 'Schrauben', …