ActiveRecord vs. SQL - Is there a cleaner way? - mysql

Question

I have a Rails 4 based application that's handling some SIEM style work for us. I'm a big believer in making code as readable as possible and then worrying about optimization. I'm finding that attempting to find all of the events that contain a set of words leads to exceptionally poor performance if I rely on AR, so I've resorted to using SQL directly even though it's fragile.
Is there a better way to do the following using AR?
sql = "select event_id from events_words where generated>'#{starting_time.to_s(:db)}' and word_id in (select id from words where words.text in ('#{terms.join("', '")}')) group by event_id having count(distinct(word_id))=#{terms.count}"
events_words is a join table containing the word_id for every word in every event, the event_id for each event and generated, the timestamp when the event was generated. The generated field is being used to limit search results to a time frame and the table itself is partitioned by date to keep the indices to a size that can fit in RAM.

Answer 1

For even better performance and readability, consider using a JOIN operation in place of the IN (subquery). To improve readability, consider qualifying every column reference.
Personally, I would find this statement to be much more "readable":
SELECT e.event_id
FROM events_words e
JOIN ( SELECT w.id
FROM words w
WHERE w.text IN ('#{terms.join("', '")}')
) s
ON s.id = e.word_id
WHERE e.generated > '#{starting_time.to_s(:db)}'
GROUP BY e.event_id
HAVING COUNT(DISTINCT(e.word_id))=#{terms.count}
... ("readability" gauged in terms of the ability of the reader to quickly figure out what the query is doing).
As to getting a query like that done in ActiveRecord (if that's possible), I am inclined to pity the poor soul that has to wade through whatever that looks like to decipher what the query is actually doing.
EDIT
After reviewing again, I see there's no need for the inline view. (That was generated from the subquery during my initial change to the JOIN operation, but that's not really necessary.
This should return an equivalent result:
SELECT e.event_id
FROM events_words e
JOIN words w
ON w.id = e.word_id
WHERE e.generated > '#{starting_time.to_s(:db)}'
AND w.text IN ('#{terms.join("', '")}')
GROUP BY e.event_id
HAVING COUNT(DISTINCT(e.word_id))=#{terms.count}

Answer 2

You might try this:
EventWord.joins(:word).
where(:words => {:text => terms}).
where("generated > ?", :starting_time).
group(:event_id).
having("count(distinct(word_id)) = ?", terms.count).
select(:event_id)
Or ...
Event.joins(:word).
where(:words => {:text => terms}).
where("generated > ?", :starting_time).
group(:id).
having("count(distinct(words.id)) = ?", terms.count)