The fastes way to sum array of integers

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Тема The fastes way to sum array of integers
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Msg-id 1355676260002-5736771.post@n5.nabble.com
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Ответы Re: The fastes way to sum array of integers
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Hi,

I sum values of array integers by query

select sum(t)
     from unnest(array[1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0]) as t
     cross join generate_series(1, 1000000);

Total runtime: 10020.699 ms

But simmilar method to count array's elements is dramatically faster

select sum(array_length(array[1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0], 1))
from generate_series(1, 1000000)

Total runtime: 464.042 ms


It's as fast as simple query!

select sum(1) from generate_series(1, 1000000)
"Total runtime: 462.687 ms"


It is possible that function e.g. array_sum written in C is as fast as
bult-in array_length?


regards
Wojciech





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