Started work on a PR that will add full-text search for a certain subset of toots (e.g. your own) https://github.com/tootsuite/mastodon/pull/6423
Still WIP because need to figure out how to introduce new database (elasticsearch) in a non-distruptive manner for poor sysadmins, and the syntax for the actual search might need some adjustment.
@val You are using postgres full-text search every time you get a username autocomplete on Mastodon. However the massive corpus of 500 character messages will seriously affect postgres both in performance and disk usage. By outsourcing this functionality to a secondary system, we're making sure this functionality will not negatively impact critical, core functionality of Mastodon.