2012/12/16 aasat <satriani@xxxxxxxxxx>: > 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? > yes - specialized function can be significantly faster - and aggregation can be calculated with significantly less iterations. Regards Pavel > > regards > Wojciech > > > > > > -- > View this message in context: http://postgresql.1045698.n5.nabble.com/The-fastes-way-to-sum-array-of-integers-tp5736771.html > Sent from the PostgreSQL - general mailing list archive at Nabble.com. > > > -- > Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-general -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
