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042-17

原创 Linux操作系统 作者:jbymy2000 时间:2012-03-14 12:38:08 0 删除 编辑
17. The SCOTT user has an index on the ITEM_DESC column of the ITEM table. As part of the year-ending task, SCOTT updates the ITEM_DESC column for most of the rows in the ITEM table. How does this change to the table affect the index?
A. An update in a leaf row takes place.
B. The index becomes invalid after the update.
C. The leaf block containing the row to be updated is marked as invalid.
D. A row in the leaf block of the index for the key value is deleted and inserted.
答案:D
每年用户一个表上的一个列,那么在这个列上的索引,行数据在索引leaf block的值会删除再被插入(估计是便于维护), 索引叶子节点包括rowid(需实验)

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