Getting SQLite3 errors even though I am trying to use PostgreSQL on Rails 3 development machine - ruby-on-rails-3

Question

Newbie question on Rails 3 development.
I am creating my first app and planning on deploying it to Heroku. Since Heroku uses PostgreSQL I thought I would change from SQLite on my development machine and move to PostgreSQL. Here is the gem file:
***source 'http://rubygems.org'
gem 'rails', '3.0.1'
gem 'pg', :require => 'pg'
gem 'devise', '1.2.0'
group :development do
gem 'rspec-rails', '2.0.1'
end
group :test do
gem 'rspec', '2.0.1'
gem 'webrat', '0.7.1'
end***
I ran a page generator but whenever I try to view the pages locally, I get the following error:
no such file to load -- sqlite3
I don't understand where this SQLite error is coming from because I commented out SQLite from the gemfile.
The bigger question is rather it is neccesary to change my database gem at all. Is it better to develop with SQLite and let the host convert the databases?
TIA

Answer 1

The problem is probably in your database.yml, I'd guess that it looks something like this:
development:
adapter: sqlite3
but you want it to look more like this:
development:
adapter: postgresql
You'll probably want to apply the same change to the test: and production: sections as well; Heroku won't pay attention to the adapter but consistency is a good idea.
As far as the second question goes, I think you're better off developing and deploying on identical platforms. You can usually get away with developing on OSX or Windows but deploying on Linux if you're careful but you should have the same gem versions, same Ruby version, same Rails version, same database (including the version!), etc. Anything else is going to cause you a lot of pain and suffering sooner or later. So, kudos for developing on PostgreSQL when you're deploying on Heroku, good call.