视图是否对PostgreSQL中的性能有害？

The danger with using views is filtering a query against a view,
expecting to read a very small portion of a very large table. Any filtering should be done within
the view because any filtering against the view itself is applied after the query in the view has
completed execution. Views are typically useful for speeding up the development process but
in the long run can completely kill database performance.

以下是PostgreSQL 9.5文档的摘录：

Making liberal use of views is a key aspect of good SQL database design. Views allow you to encapsulate
the details of the structure of your tables,which might change as your application evolves,
behind consistent interfaces.

这两个来源似乎相互矛盾(“不设计与观点”与“设计与观点”).

但是,PG视图是使用规则系统实现的.因此,可能(这是我的问题)对视图的任何过滤都被重写为视图中的过滤器,从而导致针对基础表的单个查询执行.

我的解释是否正确,PG将WHERE子句组合进出视图？或者它是一个接一个地单独运行它们？任何简短,自包含,正确(可编译)的例子？