Everything I found for optimizing pg text search performance via pg tsvector column suggested adding a postgres trigger, as described here
https://thoughtbot.com/blog/optimizing-full-text-search-with-postgres-tsvector-columns-and-triggers
class AddTsvectorColumns < ActiveRecord::Migration
def up
add_column :products, :tsv, :tsvector
add_index :products, :tsv, using: "gin"