问题描述
以下问题的答案是 C 使用 FORCESEEK 提示.但是，要使用提示，我们必须先查看执行计划，对吗?这个问题没有提到任何关于执行计划的内容.问题似乎是读者阻止作家".那么，在这种情况下，快照隔离不会有帮助吗?
The said answer for the following question is C to use FORCESEEK hint. But, to use hint, we have to review the execution plan first, right? The question doesn't mention anything about execution plan. The problem seems to be "Readers block Writers". So, won't SNAPSHOT ISOLATION help in this kind of situation?
问题:由于对具有聚集索引的频繁更新表进行查询，数据库应用程序运行缓慢.该查询返回四列:包含在非聚集索引中的 where 子句中的三列和一个附加列.优化语句
Question: A database application runs slowly because of a query against a frequently updated table that has a clustered index. The query returns four columns: three columns in its where clause contained in a non-clustered index and one additional column. To optimize the statement
- A.向查询添加 HASH 提示
- B.向查询添加 LOOP 提示
- C.向查询添加 FORCESEEK 提示
- D.向索引添加 INCLUDE 子句
- E.向附加查询添加 FORCESCAN 提示
- F.添加列存储索引以覆盖查询
- G.启用优化临时工作负载选项.
- H.将唯一聚集索引与列存储索引转换.
- 我.在运行查询之前包含 SET FORCEPLAN ON 语句
- J.在运行查询之前包含 SET STATISTICS PROFILE ON 语句
- K.在运行查询之前包含 SET STATISTICS SHOWPLAN_XML ON 语句
- L.在运行查询之前包含 SET TRANSACTION ISOLATION LEVEL REPEATABLE READ 语句
- M.在运行查询之前包含 SET TRANSADCTION ISOLATION LEVEL SNAPSHOT 语句
- N.在运行查询之前包含 SET TRANSACTION ISOLATION LEVEL SERIALIZABLE 语句
推荐答案
我会选择选项 D.因为它涵盖了表中缺失的非聚集索引.
I will go for option D. because it covers the missing non-Clusterd Index on the table.
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