Although some may argue this is a feature request, I argue it is a bug report because the result is that multi-word search does not work for normal users when Phabricator is hosted on RDS.
For all intents and purposes, search on Phabricator when hosted on RDS is not useful. Per conversation in T10589, by default, MySQL uses "OR", but this makes the search experience terrible for normal users. Phabricator raises a setup check to fix this, but the solution advised, to change the "ft_boolean_syntax" variable, is not possible on Amazon RDS because it requires super privileges.
I understand users can use the +x / +y syntax as an alternative to not being able to edit ft_boolean_syntax, and we will tell everyone on our team and hope they remember. That said, I'm sure you would agree that this is not discoverable. As you can imagine Amazon RDS is very popular (possibly the most popular hosted database service), so it would be amazing if you had a solution that worked on RDS that didn't require us to try to educate our company to use "+" in every word in a query. I don't know if a reasonable solution here is feasible, but that's what I'd recommend considering exploring.