Question

我尝试使用新数据更新旧客户数据，所以基本上我使用new_customer_source表的firstname和lastname更新old_customer_source表的firstname和lastname。

我索引了new_customer_source的custid，但我没有权限索引old_customer_source的custid。

要更新的总记录大约为50k，他们查询的时间超过30分钟！

您对如何改进下面给定的Oracle查询有任何建议吗？

update old_customer_source t1
   set   (t1.firstname, t1.lastname) = 
   (
    select  t2.firstname, t2.lastname
    from    new_customer_source t2
    where   t1.custid = t2.custid
   )
   where exists ( select 'x'
                from  new_customer_source t3
                where  t1.custid = t3.custid
              )

Answer 1

尝试使用合并。

merge into old_customer_source t1
using (select t2.custid, t2.firstname, t2.lastname
         from  new_customer_source t2
      ) t2
 on (t1.custid = t2.custid)
when matched then
update set t1.firstname = t2.firstname, 
           t1.lastname = t2.lastname
;

从另一个表更新表时的性能问题

1 个答案: