The operator does not match the specified name and type of arguments.

I have installed a Rails 3.2.x app to use PostgreSQL HStore, but I am getting an error. It looks like the hstore extension was not selected by the environment. I've already rebooted my machine, checked database extensions, etc.

When I try to execute:

User.where("settings @> (:key => :value)", :key => "setting_x", :value => "test")

      

        
        
        
      

    

I get the error: ( @>

not recognized, i.e. extension hstore

not installed?)

HINT:  No operator matches the given name and argument type(s). You might need to add explicit type casts.

      

        
        
        
      

    

Configuring My Rails Application:

Gemfile.rb:

gem 'activerecord-postgres-hstore'

      

        
        
        
      

    

Migration:

add_column :users, :settings, :hstore
execute "CREATE INDEX CONCURRENTLY users_gin_settings ON users USING GIN(settings)"
# can see the extenstion installed on my local dev psql database after this

      

        
        
        
      

    

User

model:

serialize :settings, ActiveRecord::Coders::Hstore

      

        
        
        
      

    

Dynamic methods User

:

# metaprogramming: has_setting_x + instance.setting_x
%w[setting_x setting_y setting_z].each do |key|
attr_accessible key
    # doesn't work > throws error because of the @> operator
    scope "has_#{key}", lambda { |value| where("settings @> (? => ?)", key, value) }

    # works: can use instance.setting_x
    define_method(key) do
      settings && settings[key]
    end

    # works: can use instance.setting_x = "value"
    define_method("#{key}=") do |value|
      self.settings = (settings || {}).merge(key => value)
    end
end

      

        
        
        
      

    

Update 1:

This works when I speak directly to the PostgreSQL DB:

SELECT "users".* FROM "users" WHERE (settings @> hstore('setting_x','6D9Q7RO4SVWHXK86F'));

      

        
        
        
      

    

The Hstore docs say:

The => operator is deprecated and may be removed in a future release. Use the hstore(text, text) function instead.

      

        
        
        
      

    

So, due to the look and feel, my PostgreSQL database version (9.2.1) is already outdated to refer to =>

. It looks like I have more research ahead of me.