We are not so pleased with the DPSI if we must probe multiple index trees to find rows across multiple partitions.
我们不是很乐意使用DPSI，但是我们必须跨多个分区探测多个索引树来寻找行。
2
For each author ID, an index is then used to probe whether that ID occurs in the other table.
对于每个author ID，使用索引来检查该ID是否在另一个表中出现。
3
Since Query 1 expresses the join predicate on the books table, DB2 9.1 and 9.5 perform a table scan on authors and then use the index AUTHORIDX1 to probe into the books table.