```ruby
require 'active_record'

module Songkick
  module OAuth2
    module Model
      autoload :ClientOwner,   ROOT + '/oauth2/model/client_owner'
      autoload :ResourceOwner, ROOT + '/oauth2/model/resource_owner'
      autoload :Hashing,       ROOT + '/oauth2/model/hashing'
      autoload :Authorization, ROOT + '/oauth2/model/authorization'
      autoload :Client,        ROOT + '/oauth2/model/client'
      
      Schema = Songkick::OAuth2::Schema
      
      DUPLICATE_RECORD_ERRORS = [
        /^Mysql::Error: Duplicate entry\b/,
        /\bConstraintException\b/
      ]
      
      # ActiveRecord::RecordNotUnique was introduced in Rails 3.0 so referring
      # to it while running earlier versions will raise an error. The above
      # error strings should match MySQL and SQLite errors on Rails 2. If you're
      # running a different adapter, add a suitable regex to the list:
      # 
      #     Songkick::OAuth2::Model::DUPLICATE_RECORD_ERRORS << /Postgres found a dup/
      # 
      def self.duplicate_record_error?(error)
        error.class.name == 'ActiveRecord::RecordNotUnique' or
        DUPLICATE_RECORD_ERRORS.any? { |re| re =~ error.message }
      end
      
      def self.find_access_token(access_token)
        Authorization.find_by_access_token_hash(Songkick::OAuth2.hashify(access_token))
      end
    end
  end
end

```

Add error string for duplicate key records on Postgres.
user
```ruby
require 'active_record'

module Songkick
  module OAuth2
    module Model
      autoload :ClientOwner,   ROOT + '/oauth2/model/client_owner'
      autoload :ResourceOwner, ROOT + '/oauth2/model/resource_owner'
      autoload :Hashing,       ROOT + '/oauth2/model/hashing'
      autoload :Authorization, ROOT + '/oauth2/model/authorization'
      autoload :Client,        ROOT + '/oauth2/model/client'
      
      Schema = Songkick::OAuth2::Schema
      
      DUPLICATE_RECORD_ERRORS = [
        /^Mysql::Error:\s+Duplicate\s+entry\b/,
        /^PG::Error:\s+ERROR:\s+duplicate\s+key\b/,
        /\bConstraintException\b/
      ]
      
      # ActiveRecord::RecordNotUnique was introduced in Rails 3.0 so referring
      # to it while running earlier versions will raise an error. The above
      # error strings should match MySQL and SQLite errors on Rails 2. If you're
      # running a different adapter, add a suitable regex to the list:
      # 
      #     Songkick::OAuth2::Model::DUPLICATE_RECORD_ERRORS << /DB2 found a dup/
      # 
      def self.duplicate_record_error?(error)
        error.class.name == 'ActiveRecord::RecordNotUnique' or
        DUPLICATE_RECORD_ERRORS.any? { |re| re =~ error.message }
      end
      
      def self.find_access_token(access_token)
        Authorization.find_by_access_token_hash(Songkick::OAuth2.hashify(access_token))
      end
    end
  end
end

```
assistant