In order to reduce a schedule, either the effort can be parallelized or short cuts can be taken.

为了缩短日 程，可以使工作并行化或者跳过某些阶段先行执行后面的工作。

In most cases, a query involves some operators that either cannot be parallelized, or that slow down parallel execution.

大多数情况下，查询包含某些无法进行并行化或会减慢并行执行速度的运算符。