Filtering notes using hashtag combinations and hashtags with underscore doesn't work as expected

[caugner]

We have been creating notes using the hashtags #caresteouvert and #DE to easily filter notes created by the Ca reste ouvert project by country.

➡️ Unfortunately querying notes for #caresteouvert #DE didn't properly filter using these hashtags, but instead using the words caresteouvert and de (as in "details").

As a reaction, we changed the hashtagging to #caresteouvert #caresteouvert_DE.

➡️ Unfortunately querying notes for #caresteouvert_DE still had exactly the same result.

As a workaround, we will probably migrate to #caresteouvertDE, but it would be great if the Notes API filtering implementation could be adjusted to better accoung for hashtags and hashtags including underscores.

See also: ENT8R/NotesReview#57

According to @ENT8R, the search string filtering happens here (which might be where the fix could happen):

openstreetmap-website/app/controllers/api/notes_controller.rb

Line 277 in 8199002

@notes = @notes.joins(:comments).where("to_tsvector('english', note_comments.body) @@ plainto_tsquery('english', ?)", params[:q]) if params[:q]

[ENT8R]

Actually, this is quite similar to #2585
The search method is so simple that it doesn't suit most use cases. I also have no clue if it would be a good idea to add additional logic to the search... Maybe it would be better to use a different service than the API directly in order to search and filter notes (and show them in the interface of NotesReview), like @tomhughes already pointed out in #2585. The only problem is that I'm not aware of any service like that.
I really would like to work on something similar, the only thing that keeps me from doing is, is that the notes database dump is only generated on a daily basis. It is nice that they are exported every day, but often this seems to be a long time. @tomhughes Is there some possibility to get the notes from the database in real time?
One way I could think of is simply fetching the notes from the API in a given interval by the time they were last updated (https://api.openstreetmap.org/api/0.6/notes/search.json?sort=updated_at) and importing it in some kind of database.

[tomhughes]

Duplicate of #2585.