Is there a search function?

and if so how does it work?

It’s the magnifying glass at top right. Click Options for pop-up help.

thanks. it looks like the search scans all text which is more of a CPU hog, but it makes finding stuff so much better.

How do I get rid of my email address that shows in my profile page ?

Nobody else except admins can see your email. If you look at your profile while not logged in you can see it’s hidden.

Not quite - it uses the sql database’s built-in “full text search engine” with “stemming”, which makes the CPU impact negligible (which is why search is available to anonymous users).

Interesting. Which DBMS is it?

Discourse runs with a Postgres database. Here’s the documentation on the full-text search features: