过滤查询以及聚合

A natural extension to aggregation scoping is filtering. Because the aggregation operates in the context of the query scope, any filter applied to the query will also apply to the aggregation. 过滤是聚合作用域的一个很自然的扩展。因为聚合工作在查询作用域的上下文中，那么适用于查询的任何过滤器也同样能够适用于聚合。 A natural extension to aggrega