Cached dataset

I have about 100 mostly static tables in my application.
It takes about 1 minutes to download them through internet.

So I think I need to cahce those tables in local hard drive.
However, in this case refresh must be done before table access when those
tables are changed in server.

MS SQL .NET data provider implements cacheable interface which allows this.
Dataset is automatically refreshed using polling or async event notificaton.

I read the npgsql docs but havent found such feature.

Where to find sample which implements cached dataset in Postgres ?

Andrus.