如何将原始 SQL 附加到现有的 Rails ActiveRecord 链？

Question

I have a rule builder that ultimately builds up ActiveRecord queries by chaining multiple where calls, like so:

Track.where("tracks.popularity < ?", 1).where("(audio_features ->> 'valence')::numeric between ? and ?", 2, 5)

Then, if someone wants to sort the results randomly, it would append order("random()") .

However, given the table size, random() is extremely inefficient for ordering, so I need to use Postgres TABLESAMPLE-ing.

In a raw SQL query, that looks like this:

SELECT * FROM "tracks" TABLESAMPLE SYSTEM(0.1) LIMIT 250;

Is there some way to add that TABLESAMPLE SYSTEM(0.1) to the existing chain of ActiveRecord calls? Putting it inside a where() or order() doesn't work since it's not a WHERE or ORDER BY function.

Answer 1

irb(main):004:0> Track.from('"tracks" TABLESAMPLE SYSTEM(0.1)')
  Track Load (0.7ms)  SELECT "tracks".* FROM "tracks" TABLESAMPLE SYSTEM(0.1) LIMIT $1  [["LIMIT", 11]]