有了这个特性，查询优化器可以在决定访问计划时立即考虑索引。

With this feature, the query optimizer can immediately consider the index when determining an access plan.

youdao

如果立即建立索引，则需要扫描表空间，这样要花费比较多的时间。

If you build the index immediately, the table space is scanned, which can take a considerable amount of time.

youdao

它让DB 2使用索引来立即查找满足where子句中的两个简单谓词的行。

It lets DB2 use the index to immediately look up the row or rows that satisfy the two simple predicates in the WHERE clause.

youdao