需要帮助调整查询 - 使用连接字段的左连接效率不高

Question

我编写了一个查询，在该查询中从总体中过滤掉记录，其中嵌套查询中的 2 个字段的值等于表中的 2 个对应字段。我正在尝试使用 2 个关键字段的串联作为查找。

虽然这确实让我得到了我正在寻找的结果，但这种方法似乎效率很低，因为查询需要大约 60 秒才能返回结果（CRM.ASSET_PLUS 表有超过 10M 的记录）。假设我无法过滤掉任何内容，并且没有在 CRM.ASSET_PLUS 中创建自定义字段，并且这两个字段已经连接。

有没有更好的方法可以做到这一点？

SELECT DISTINCT A.ACCOUNT_NUMBER
  FROM (SELECT C.ACCOUNT_NUMBER,
               A.LOCATION_ACCOUNT_ID || A.PRODUCT_ID AS LOOKUP
          FROM CRM.ASSET_PLUS A,
               CRM.PROD_INT B,
               CRM.ACCOUNT C,
               CRM.ACCOUNT D
         WHERE A.PRODUCT_ID = B.ROW_ID
           AND A.LOCATION_ACCOUNT_ID = C.ACCOUNT_ID
           AND C.PARENT_ID = D.ACCOUNT_ID
           AND D.ACCOUNT_NUMBER = '00750333'
       ) A
   LEFT JOIN (SELECT A.LOCATION_ACCT_ID || A.PRODUCT_ID AS LOOKUP
                FROM ORDER_FORM_PRODUCTS A
               WHERE A.AGREEMENT_NUM = '00750333_JUN2014'
             ) B
     ON A.LOOKUP = B.LOOKUP
  WHERE B.LOOKUP IS NULL;

Answer 1

尝试连接多个字段，而不是连接

SELECT DISTINCT
    A.ACCOUNT_NUMBER
FROM 
    CRM.ASSET_PLUS A,
    CRM.PROD_INT B,
    CRM.ACCOUNT C,
    CRM.ACCOUNT D
LEFT JOIN ORDER_FORM_PRODUCTS E 
    ON (E.LOCATION_ACCOUNT_ID = A.LOCATION_ACCOUNT_ID
       OR (E.LOCATION_ACCOUNT_ID IS NULL AND A.LOCATION_ACCOUNT_ID IS NULL))
    AND (E.PRODUCT_ID = A.PRODUCT_ID 
        OR (E.PRODUCT_ID IS NULL AND A.PRODUCT_ID IS NULL))
    AND E.AGREEMENT_NUM = '00750333_JUN2014'
WHERE 
    A.PRODUCT_ID = B.ROW_ID 
    AND A.LOCATION_ACCOUNT_ID = C.ACCOUNT_ID
    AND C.PARENT_ID = D.ACCOUNT_ID
    AND D.ACCOUNT_NUMBER = '00750333'
    AND E.LOCATION_ACCOUNT_ID IS NULL
    AND E.PRODUCT_ID IS NULL

为了清楚起见，我建议您明确加入

SELECT DISTINCT
    A.ACCOUNT_NUMBER
FROM 
    CRM.ASSET_PLUS A
    JOIN CRM.PROD_INT B ON A.PRODUCT_ID = B.ROW_ID
    JOIN CRM.ACCOUNT C ON A.LOCATION_ACCOUNT_ID = C.ACCOUNT_ID
    JOIN CRM.ACCOUNT D ON C.PARENT_ID = D.ACCOUNT_ID
        AND D.ACCOUNT_NUMBER = '00750333'
    LEFT JOIN ORDER_FORM_PRODUCTS E 
       ON (E.LOCATION_ACCOUNT_ID = A.LOCATION_ACCOUNT_ID
         OR (E.LOCATION_ACCOUNT_ID IS NULL AND A.LOCATION_ACCOUNT_ID IS NULL))
       AND (E.PRODUCT_ID = A.PRODUCT_ID 
         OR (E.PRODUCT_ID IS NULL AND A.PRODUCT_ID IS NULL))
       AND E.AGREEMENT_NUM = '00750333_JUN2014'
WHERE 
    E.LOCATION_ACCOUNT_ID IS NULL
    AND E.PRODUCT_ID IS NULL