Oh sorry wait a sec, I missed your customization inside ecto function, sec, let me fix it.
maxim
maxim
Ok check my post above, I edited it in a way that should work. Let me know if something is wrong again, happy to help get it working.
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jonathanleang
I customized Enum.reduce in ecto_in_batches_by_id and got it working, thanks for your help.
|> Enum.reduce({-1, 0}, fn r, {_, i} → {elem(elem(r, 0), 1), i + 1} end)
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maxim
Oh you’re right! That function always expects id as the first item, and if I rearrange select fields it won’t work. Great find! However, I don’t recommend customizing the function because it’s meant to be reusable in any place where you need to stream data from database. Instead I suggest to go back to what you were doing originally, but it’s much simpler now:
def leaderboard_stream() do
import Ecto.Query, only: [from: 2]
query = from(r in Darkmoor.User, select: {r.id, r.elo, r.name})
Darkmoor.Repo
|> StreamExt.ecto(query, batch_size: 5, strategy: :id)
|> Stream.map(fn {id, elo, name} -> {{elo, id}, name} end)
end
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jonathanleang
jonathanleang
I have an other question.
Currently the smaller or more negative the score is the higher the rank is, how do I rank the player higher, the higher the score is ?
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maxim
Notice how in the README example the scores are all negative. I didn’t want to implement any special sorting logic, and instead left this simply up to the user, so all you need to do is put a minus in front of your scores, then map them back (minus again) when getting them for display.
Example:
def leaderboard_stream() do
import Ecto.Query, only: [from: 2]
query = from(r in Darkmoor.User, select: {r.id, r.elo, r.name})
Darkmoor.Repo
|> StreamExt.ecto(query, batch_size: 5, strategy: :id)
|> Stream.map(fn {id, elo, name} -> {{-elo, id}, name} end) # <=== minus added on this line
end
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jonathanleang
jonathanleang
Hi there, we just launched our game and got featured on the app store, the CPU load is really high and our leaderboard controller is taking up most of the time.
is there any quick fix, our server is hosted on DigitalOcean 8 cores now, and soon there will be no bigger instance to upgrade to, we have been doubling the traffic every 1-2 days, the leaderboard seems to run much faster on MBP maybe memory bandwidth is much lower on vm.
leaderboard = Leaderboard.client_for(country)
globalResult = ConCache.get_or_store(:room, "leaderboard"<>Atom.to_string(country), fn() ->
leaderboard
|> Leaderboard.top()
|> Enum.take(topranklimitInt)
end)
nearResult = ConCache.get_or_store(:room, "leaderboard"<>Integer.to_string(user_id)<>Atom.to_string(country), fn() ->
Leaderboard.get(leaderboard, user_id, first..last)
end)
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maxim
Are you inserting values dynamically? The entire leaderboard is recalculated on each insert, it’s meant for rare writes and frequent reads.
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