CREATE CACHE GROUP文でのWHERE句の適切な配置

複数表のキャッシュ・グループでは、特定の表定義内のWHERE句で、キャッシュ・グループ内のその表以外の表を参照することはできません。たとえば、次のCREATE CACHE GROUP文は有効です。

CREATE READONLY CACHE GROUP customer_orders
FROM sales.customer
 (cust_num NUMBER(6) NOT NULL,
  region   VARCHAR2(10),
  name     VARCHAR2(50),
  address  VARCHAR2(100),
  PRIMARY KEY(cust_num))
  WHERE (sales.customer.cust_num < 100),
sales.orders
 (ord_num      NUMBER(10) NOT NULL,
  cust_num     NUMBER(6) NOT NULL,
  when_placed  DATE NOT NULL,
  when_shipped DATE NOT NULL,
  PRIMARY KEY(ord_num),
  FOREIGN KEY(cust_num) REFERENCES sales.customer(cust_num));

CREATE READONLY CACHE GROUP customer_orders
FROM sales.customer
 (cust_num NUMBER(6) NOT NULL,
  region   VARCHAR2(10),
  name     VARCHAR2(50),
  address  VARCHAR2(100),
  PRIMARY KEY(cust_num)),
sales.orders
 (ord_num      NUMBER(10) NOT NULL,
  cust_num     NUMBER(6) NOT NULL,
  when_placed  DATE NOT NULL,
  when_shipped DATE NOT NULL,
  PRIMARY KEY(ord_num),
  FOREIGN KEY(cust_num) REFERENCES sales.customer(cust_num))
  WHERE (sales.orders.cust_num < 100);

次の文は、子表の定義内のWHERE句が親表を参照しているため無効です。

CREATE READONLY CACHE GROUP customer_orders
FROM sales.customer
 (cust_num NUMBER(6) NOT NULL,
  region   VARCHAR2(10),
  name     VARCHAR2(50),
  address  VARCHAR2(100),
  PRIMARY KEY(cust_num)),
sales.orders
 (ord_num      NUMBER(10) NOT NULL,
  cust_num     NUMBER(6) NOT NULL,
  when_placed  DATE NOT NULL,
  when_shipped DATE NOT NULL,
  PRIMARY KEY(ord_num),
  FOREIGN KEY(cust_num) REFERENCES sales.customer(cust_num))
  WHERE (sales.customer.cust_num < 100);

同様に、次の文は、親表の定義内のWHERE句が子表を参照しているため無効です。

CREATE READONLY CACHE GROUP customer_orders
FROM sales.customer
 (cust_num NUMBER(6) NOT NULL,
  region   VARCHAR2(10),
  name     VARCHAR2(50),
  address  VARCHAR2(100),
  PRIMARY KEY(cust_num))
  WHERE (sales.orders.cust_num < 100),
sales.orders
 (ord_num      NUMBER(10) NOT NULL,
  cust_num     NUMBER(6) NOT NULL,
  when_placed  DATE NOT NULL,
  when_shipped DATE NOT NULL,
  PRIMARY KEY(ord_num),
  FOREIGN KEY(cust_num) REFERENCES sales.customer(cust_num));