Why would you use Postgres for this which doesn't horizontally scale when you could easily index documents in ES and use that for full text search?
http://rachbelaid.com/postgres-full-text-search-is-good-enou...
I read this article about 6 years ago and after an afternoon I added full-text search to the app I worked on at the time. 6 years later, it's still the only search they use. This small tool already built into postgres has been more than enough for us.
Unfortunately, many will, due to FOMO and Resume Driven Development.