What's the right way to do counts in Rails?

You don't need a name scope to perform a count.

Account.where(:admin => false).count

But named scopes are an excellent way to make your code more reusable.

Named scopes don't have any noticeable performance impact on your application.

I would recommend you to avoid direct access to database in my templates because then you're losing a bit of flexibility when it comes to caching.

Try to prepare all the data you need to render in your action instead and then use meaningful instance variables like @number_of_accounts or @accounts.count.

This will make your views cleaner and easier to debug and also a bit more DRY if you render action in different formats (html, json, etc)

As to how do you get your numbers - it doesn't really matter that much, just move away from find_* methods towards scoping and write readable code

In rails 3 a simple call to count issues a simple count request:

Contact.count

is resolved as:

SELECT COUNT(*) AS count_id FROM "contacts"

a find all by field name will resolve as:

Contact.find_all_by_country("Canada")SELECT "contacts".* FROM "contacts" WHERE ("contacts"."country" = 'Canada')

I would recommend indexing your admin column for faster lookups and this can be translated into a named scope, but that by itself will only predefine the query, not optimize it.

It is important to note that if you issue

Contact.find_all_by_country("Canada").count

count is a method on the array class and doesn't actually issue a count on the database:

Contact.find_all_by_country("Canada").countSELECT "contacts".* FROM "contacts" WHERE ("contacts"."country" = 'Canada')