Set ranking rules at search time

[loiclec]

Summary

I would like to be able to set the ranking rules at search time, possibly with a new search parameter: rankingRules.

• If this parameter is not set (or = null), then the settings' ranking rules will be used
• If it is set, then the search query will be executed using the provided ranking rules

Why

• There are no technical reasons for not being able to set the ranking rules at search time
• It would prove useful for users who want experiment with different ranking rules quickly and fine-tune the relevancy of their search results. Changing the ranking rules via a settingsUpdate task could take a very long time if a lot of indexing tasks are already enqueued. Doing it via a search parameter, on the other hand, is instant and does not modify the index.
• Quoting @gmourier: "[we could] customise the search experience PER user / user group thanks to tenant tokens (rankingRules would be a property of the tenant token, which would be enforced at search-time when it is used to authenticate the request)"

Caveats

1. It could be dangerous to allow anyone to set arbitrary ranking rules due to performance (and therefore DoS) issues. This can be solved in two ways: (1) limit who can set custom ranking rules; or (2) make sure that searches stay quick no matter what ranking rules are used (my preferred solution)

2. Currently, one can add a custom ranking rule my_field:asc even if my_field is neither filterable nor sortable. This would not be possible at search time.

[tacman]

Here's an example of what I think is a pretty common use case. I want to find Symfony bundles for working with APIs, so I set the search to "api"

https://packages.survos.com/?q=api&marking=symfony_ok

I'd like to look at the most widely-used ones first, so I sort by number of downloads. As I'm scrolling down, I suddenly see the number of downloads changes, which jumps out as a bug. But if you look at ranking, it's right. So while I could reset the index to be prioritize sorting, most of the time I don't want to -- it's a runtime setting, not an index build setting.

I think this is really common -- sort by price, rating, time, combine with a full-text search. Please consider making it a run-time option, even if there is a cost associated with pagination.

[tacman]

Here's an example on a single page: https://packages.survos.com/?q=payment&marking=symfony_ok

Sorting by downloads (by clicking on the title) looks like it's broken.