There've been quite a few complaints about the existing forum search. So I thought I'd write my own as a fun side project.
You can see the result here:
https://hlp-search.tproxy.de/It's indexing every publicly available post. However, the indexing process hasn't finished (at the time of writing) so quite a few posts might be missing. The above link will let you know how far along the indexing process is.
The search engine itself is fairly straightforward. You enter you search query and get results. Advanced searches (i.e. find this -but -not -this, "Find this exact sentence.", show only results where +this word appears, etc.) are also possible.
Here's the full documentation of the query syntax. The input field has autocomplete but that's just based on all of the indexed thread titles so it might lead to some interesting results. You'll also get suggestions like "Did you mean ...?" if you misspelled something.
Anyway, this was a fun project. Let me know if this is actually useful to anyone, if you're interested in the source code / how it works or want some kind of change.
EDIT: Mentioned issues were fixed. New posts are added to the index every 2 hours.