CakePHP: Optymalizacja tabel ACL

Natknąłem się w sieci na ciekawy kawałek kodu SQL, który drastycznie zwiększa wydajność zapytań do tabel ACL. Zmiana polega jedynie na nałożeniu indeksów i kluczy obcych. Kod został znaleziony na grupie dyskusyjnej CakePHP.

/* ACL Tables */
 
CREATE TABLE acos (
    id INT UNSIGNED AUTO_INCREMENT NOT NULL PRIMARY KEY,
    parent_id INT DEFAULT NULL,
    model VARCHAR(255) DEFAULT '',
    foreign_key INT UNSIGNED DEFAULT NULL,
    alias VARCHAR(255) DEFAULT '',
    lft INT DEFAULT NULL,
    rght INT DEFAULT NULL
) ENGINE = INNODB;
-- table name is quoted because it is a reserved word
CREATE INDEX idx_acos_lft_rght ON `acos`(lft,rght);
CREATE INDEX idx_acos_alias ON `acos`(alias);
CREATE INDEX idx_acos_model_foreign_key ON `acos`(model(255),foreign_key);
 
CREATE TABLE aros (
    id INT UNSIGNED AUTO_INCREMENT NOT NULL PRIMARY KEY,
    parent_id INT DEFAULT NULL,
    model VARCHAR(255) DEFAULT '',
    foreign_key INT UNSIGNED DEFAULT NULL,
    alias VARCHAR(255) DEFAULT '',
    lft INT DEFAULT NULL,
    rght INT DEFAULT NULL
) ENGINE = INNODB;
-- table name is quoted because it is a reserved word
CREATE INDEX idx_aros_lft_rght ON `aros`(lft,rght);
CREATE INDEX idx_aros_alias ON `aros`(alias);
CREATE INDEX idx_aros_model_foreign_key ON `aros`(model(255),foreign_key);
 
CREATE TABLE aros_acos (
    id INT UNSIGNED AUTO_INCREMENT NOT NULL PRIMARY KEY,
    aro_id INT UNSIGNED NOT NULL,
    aco_id INT UNSIGNED NOT NULL,
    _create CHAR(2) NOT NULL DEFAULT 0,
    _read CHAR(2) NOT NULL DEFAULT 0,
    _update CHAR(2) NOT NULL DEFAULT 0,
    _delete CHAR(2) NOT NULL DEFAULT 0
) ENGINE = INNODB;
-- table names are quoted because they are reserved words
CREATE UNIQUE INDEX idx_aros_acos_aro_id_aco_id ON `aros_acos`(aro_id, aco_id);
ALTER TABLE aros_acos ADD CONSTRAINT FOREIGN KEY (aro_id) REFERENCES `aros`(id);
ALTER TABLE aros_acos ADD CONSTRAINT FOREIGN KEY (aco_id) REFERENCES `acos`(id);