基准测试时，规则1总是使优化。

When benchmarking, rule 1 is always enable optimizations.

youdao

为使优化器能够使用可用的分布统计信息，带有具体值的谓词极为重要。

Predicates with concrete values are important for the optimizer to be able to use available distribution statistics.

youdao

上面表达式使优化器不能有效分配基数或选择性消耗，可能会反过来影响整个执行计划。

These expressions prevent the optimizer from assigning valid cardinality or selectivity estimates and can in turn affect the overall plan and the join method.

youdao