在 Oracle 中强制使用索引
我在面试中遇到了这个问题，不知道如何回答:
I encountered this question in an interview and had no clue how to answer:
有一个表，在列上有一个索引，你查询:
There is a table which has a index on a column, and you query:
select * from table_name where column_having_index="some value";
查询时间太长，你发现索引没有被使用.如果你认为使用索引查询的性能会更好，你怎么能强制查询使用索引?
The query takes too long, and you find out that the index is not being used. If you think the performance of the query will be better using the index, how could you force the query to use the index?
推荐答案
您可以使用优化器提示
select/*+ INDEX(table_name index_name) */from table etc...
更多关于使用优化器提示:http://download.oracle.com/docs/cd/B19306_01/server.102/b14211/hintsref.htm
More on using optimizer hints: http://download.oracle.com/docs/cd/B19306_01/server.102/b14211/hintsref.htm
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