rails 3 meta_search usage

I am in the process of upgrading my app from Rails2 to Rails3.
My Rails2 app uses searchlogic heavily.
After googling i've come to know that searchlogic is not compatible
with Rails3 and need to use meta_search instead.

But i havent quite understood the usage of meta_search vis-a-vis

If i have a User model with :name and :address fields, i am not able
to use the following methods with meta_search. What am i doing wrong?

ruby-1.9.2-p0 > User.name_null
NoMethodError: undefined method `name_null' for #<Class:
from /home/pratik/.rvm/gems/ruby-1.9.2-p0/gems/activerecord-3.0.3/lib/
active_record/base.rb:1008:in `method_missing'
from (irb):7
from /home/pratik/.rvm/gems/ruby-1.9.2-p0/gems/railties-3.0.3/lib/
rails/commands/console.rb:44:in `start'
from /home/pratik/.rvm/gems/ruby-1.9.2-p0/gems/railties-3.0.3/lib/
rails/commands/console.rb:8:in `start'
from /home/pratik/.rvm/gems/ruby-1.9.2-p0/gems/railties-3.0.3/lib/
rails/commands.rb:23:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'

None of the methods like User.user_id_eq(1) or
User.name_equals("Blah") are working. I guess i havent understood the
usage of meta_search yet!

meta_search https://github.com/ernie/meta_search

I've never actually heard of either of those, but is there something
different that

User.name_equals("blah") gives you that you can't get with

User.where(:name => 'blah')