Rails Update More Effiecient - ruby-on-rails-4

Question

I need to update all my entries every 5 minutes. I am using Rails version 4.2.5 and Ruby version 2.3.0. My code below has worked fine with a small number of entries. I have about 800 entries now and it is taking up to 2 minutes to update. Is there a more efficient way?
#players = Entry.all
for player in #players
sort = 0
#player_selection = Selection.includes(:golfer).where("entry_id = ?", player.id).order('golfers.score asc').all
for selection in #player_selection
sort += 1
score_sort = Selection.where("id = ?", selection.id).first
score_sort.sort = sort
score_sort.save
player = Entry.where("id = ?", selection.entry_id).first
player.score = Selection.includes(:golfer).where("entry_id = ? and selections.sort < 6", selection.entry_id).sum('golfers.score')
player.save
end
end
Thank you.

Answer 1

Seems to me that you could offload some of your work to when records are created and/or updated (instead of aggregating them on a schedule).
e.g. something like:
# I assume your relationship is something like this:
class Golfer
belongs_to :entry
after_create :update_scores
after_update :update_scores
private
def update_scores
entry.update(score: entry.golphers.sum(:score))
end
end
This will reduce the workload when you run your sort update process.
Then your sort update process could be streamlined:
#entries = Entry.all
#entries.each do |entry|
sort = 0
#selections = Selection.includes(:golfer).where("entry_id = ?", player.id).order('golfers.score asc')
#selections.each do |selection|
sort += 1
selection.update(sort: sort)
end
end
by removing the extraneous data request, this will slightly improve the operation. However, your current operations are going to be linear at-best because you are running it as loop: (O)n + 1 runtime. You would likely have to drop into SQL to have a significantly faster computation:
# -> SQL; depends on DB a bit
UPDATE selections s
s.sort = ns.new_sort
FROM
(SELECT id, ROW_NUMBER() OVER (ORDER BY score ASC) AS new_sort
from selection) as nt
you could run a pure SQL command using Rails, as such:
# Be careful, this is dangerous
sql = "UPDATE ... your sql query here"
ActiveRecord::Base.connection.execute(sql)