My project is structured as follows:

DAL

public IQueryable<Post> GetPosts()
{
        var posts = from p in context.Post select p;

        return posts;
}

Service

public IList<Post> GetPosts()
{
        var posts = repository.GetPosts().ToList();

        return posts;
}

//Returns a list of the latest feeds, restricted by the count.
public IList<PostFeed> GetPostFeeds(int latestCount)
{
       List<Post> post - GetPosts();

       //CODE TO CREATE FEEDS HERE

       return feeds;

}

Lets say the GetPostFeeds(5) is supposed to return the 5 latest feeds. By going up the list, doesn't it pull down every single post from the database from GetPosts(), just to extract 5 from it?

If each post is say 5kb from the database, and there is 1 million records. Wont that be 5GB of ram being used per call to GetPostFeeds()?

Is this the way it happens? Should I go back to my DAL and write queries that return only what I need?