Building indexes

You must use GIN or GIST indexes for full text search.

Essentially you look in a SQL statement for the operator (% or @@) and grab the operand that isn't the query.

Then you do something like this:

CREATE INDEX my_cool_index ON my_cool_table USING gist (([expression]));

or (for trigram only)

CREATE INDEX my_cool_index ON my_cool_table USING gist (([expression]) pg_trgm_ops);

Trigram seems to underperform the other types.

You can also use a trigger to automatically populate a column of type tsvector with the [expression] from above, and then use the :tsvector_column option in pg_search to tell it to use that column instead. Then you'd make a very similar index as the above but put the column in instead of [expression]

You'll need enough columns in your table for EXPLAIN ANALYZE to show up using the index, and the index is brittle on the expression, so if you change the pg_search configuration, you'll have to change the index.

With ActiveRecord and/or Rails

As of ActiveRecord 4.0, you can add indexes and specify the "type" of index:

add_index(:posts, :tsv_body, using: 'gin')

For the triggers, you can use hair_trigger to add database triggers via your migrations:

create_trigger(compatibility: 1).on(:posts).before(:insert, :update) do
  "tsvector_update_trigger(tsv_body, 'pg_catalog.english', body);"
end