Building a search for your rails app can become a touch complicated when you need to order by relevancy. Solr reduces this complexity by moving the heavy lifting off to it's own service. It's fairly quick & the rails wrapper has keeps things very tidy, however with a handful of small tweaks you can make it a touch more reliable and a little quicker.

For this article, I'm assuming you've already setup sunspot_rails on your rails app and you just want to know a few tweaks I found worthwhile in my Heroku environment.

Reindex with a worker

I like to use WebSolr (It's an Heroku Addon), it's pretty awesome but from time to time it does throw 50x errors (especially when I've been hitting their service a little hard). To stop the end user seeing the 503 errors, setup the solr_index method to run asynchronously like so:

class Post < ActiveRecord::Base
  searchable do
    string :title
    text :body
    time :published_at
  end

  handle_asynchronously :solr_index
end

This means, that if the solr service returns a 50x error it'll try again a few seconds later & the end user shouldn't notice the issue. Also I don't add in :solr_index!, as when I've had both methods running asynchronously I noticed my memory usage growing very rapidly.

 Only reindex when a limited amount of attributes change

Odds are you'll only be searching against a few attributes within your model, to tell solr to only reindex when it sees these attributes have changed, use the only_reindex_attribute_changes_of argument with an array of symbols.

class Post < ActiveRecord::Base
  searchable only_reindex_attribute_changes_of: [:title, :body, :published_at] do
    string :title
    text :body
    time :published_at
  end
end

 Only index what you need

Use the if argument with a proc to only index models that should be in your results.

class Post < ActiveRecord::Base
  searchable if: proc { |post| post.published?  } do
    string :title
    text :body
    time :published_at
  end
end

In this case, if the post isn't published it will be omitted from the search index completely.

Improving indexing speed with includes

If you're calling a relationship within your searchable block, use the include argument. It eager loads in the associated models

class Post < ActiveRecord::Base
  searchable include: [:categories, :author] do
    string :title
    string :author_name do
      author.name
    end
    string :categories_list do
      categories.map(&:name).join(", ")
    end
    text :body
    time :published_at
  end
end