Change search result ranking

[kineticsquid]

I recently received a complaint about an extension that was misleading. It was a republication of a popular extension, sight changes to package.json, but otheriwse no changes to name, displayname or any of the links. And because it was new, it was showing up first in the search results, ahead of the much more popular extension. I'm recommending we change our search ranking to more heavily, or completely, weight on download count.

@filiptronicek @spoenemann @amvanbaren Thoughts?

[filiptronicek]

@amvanbaren did some changes to sorting last year in eclipse/openvsx#672, but IIRC that was just for sorting by "Rating". I'm not sure what we sort by now by default, but download count should definitely be one of the main factors we take a look at (besides probably string distance).

[amvanbaren]

By default it sorts by relevance, which is a combination of multiple weighting factors: https://github.com/eclipse/openvsx/blob/072bf3e7fa38eef217ebb30d9748f5556440c665/server/src/main/java/org/eclipse/openvsx/search/RelevanceService.java#L39-L48

This is how the relevance rating is calculated: https://github.com/eclipse/openvsx/blob/072bf3e7fa38eef217ebb30d9748f5556440c665/server/src/main/java/org/eclipse/openvsx/search/RelevanceService.java#L73-L109

The timestamp factor is the leading relevance factor for the open-vsx.org deployment:

open-vsx.org/configuration/application.yml

Lines 177 to 181 in 43c654c

	search:
	relevance:
	rating: 0.2
	downloads: 1.0
	timestamp: 3.0

[kineticsquid]

IMO downloads should be most heavily weighted. Not sure of the values though.

[filiptronicek]

I'd propose that we switch the open-vsx.org deployment to the following:

 rating: 0.5
 downloads: 2.0
 timestamp: 1.2

This is as arbitrary as it gets, but it feels like we should make ratings and downloads the primary metrics and only have the timestamp secondary, since besides indicating that an extension is more "up-to-date", it does not signal much.

[kineticsquid]

Here's a PR with those changes: #3206