“Heroku’s documentation lists two ways to get full text indexing working with your Heroku application. They talk about using Ferret and Solr for full text indexes. The Ferret option looks OK, but it requires you to rebuild your indexes every time you push. Solr would work, but it requires an EC2 instance or some third party server. Since my budget is precisely $0, using Solr is out of the picture.
But there is a third option. A very secret option. A devious but fun option. You see, Heroku runs PostgreSQL for each rails application database. They’re running a version new enough (Version 8.3) to have full text index support built in. If we’re willing to throw out database agnosticism, we can take advantage of the database’s indexing capability. [...]” 1
If you have several models you want to search through in one go, one approach is to use a separate search model. First populate a database view with the models you want to search through:
Now we can write our Search model:
Search.new('awesome') will return all authors AND books that have 'awesome' in their name or title.
If you don't wish to search across all your text columns, you an include Searchable with a list of columns to whitelist in searches:
As you can see, _why can't be found.
It's also possible to limit which columns are searched through judicious use of scopes: