For the exceptional situations where the optimizer cannot choose an optimal query execution plan, DB2 has added features such as the SELECTIVITY clause and optimization guidelines.

对于优化器不能选择最佳查询执行计划的例外情况，DB 2已经增加了诸如selectivity子句和优化指南之类的特性。

youdao

For the exceptional situations where the optimizer cannot choose an optimal query execution plan, DB2 has added features such as the SELECTIVITY clause and optimization guidelines.

对于优化器不能选择最佳查询执行计划的例外情况，DB 2已经增加了诸如selectivity子句和优化指南之类的特性。

youdao