如何提高尋找參考表名

Question

Oracle查詢的性能得到了我下面的查詢：

SELECT TABLE_NAME, CONSTRAINT_NAME FROM USER_CONSTRAINTS 
WHERE R_OWNER = 'OWNERNAME' AND STATUS ='ENABLED' AND CONSTRAINT_TYPE = 'R' 
AND R_CONSTRAINT_NAME IN (SELECT CONSTRAINT_NAME FROM ALL_CONSTRAINTS 
WHERE CONSTRAINT_TYPE IN ('P', 'U') AND TABLE_NAME = 'REGIONS' 
AND OWNER = 'OWNERNAME') 

花了4秒]得到它的輸出。

有沒有更好的方法來獲取參考表名稱的名稱？

在此先感謝。

俊

Answer 1

有一個聯接條件查詢中丟失：

SELECT TABLE_NAME, 
     CONSTRAINT_NAME 
FROM USER_CONSTRAINTS 
WHERE R_OWNER = 'OWNERNAME' 
    AND STATUS ='ENABLED' 
    AND CONSTRAINT_TYPE = 'R' 
    AND (R_OWNER, R_CONSTRAINT_NAME) IN (SELECT OWNER, CONSTRAINT_NAME 
             FROM ALL_CONSTRAINTS 
             WHERE CONSTRAINT_TYPE IN ('P', 'U')  
              AND TABLE_NAME = 'REGIONS' 
              AND OWNER = 'OWNERNAME') 

你不限制R_OWNER爲「OWNERNAME」，這是指有看所有約束模式中的OWNERNAME不只有那些鏈接到OWNERNAME.REGIONS表的鏈接。