[erlang-questions] Efficient sum matrix by column

Grigory Fateyev <>
Sun Apr 12 19:53:11 CEST 2015


Hello Alexander Petrovsky!
On Sun, 12 Apr 2015 21:23:09 +0400 you wrote:

> Hello!
> 
> I have about 100 nodes in cluster, each node in cluster contains about
> 100000 elements in proplist. All proplists have equal length, the same
> keys, but different values. I need to get the sum values for every key
> between all proplists. By example, it can be represented as matrix NxM
> (N~=100, M~=100000), and I need to get the sum by column.
> 
> The problem is that it's too slow, even when I use the hackish way
> with ets:update_counter and N=2, it's take about 1.5 secs, If I make
> in parallel, it's take about 2-3 seconds.
> 
> How can I make it fast and efficient?
> 

Look at lists:keyfind/4 It is much faster than proplists.

-- 
Best regards!
gfborn [at] gmail [dot] com


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