On Wed, Apr 27, 2011 at 18:06, Merlin Moncure <mmoncure@xxxxxxxxx> wrote: > On Wed, Apr 27, 2011 at 12:00 PM, Adrian Schreyer <ams214@xxxxxxxxx> wrote: >> The largest arrays I expect at the moment are more or less sparse >> vectors of around 4.8k elements and I have noticed that the >> input/output (C/C++ extension) does not scale well with the number of >> elements in the array. >> >> Using a function that sums all elements in the array, this is the time >> it takes for ~150k arrays of various sizes (including ordering desc >> and limit 10): >> >> 128: 61ms >> 256: 80ms >> 512: 681ms >> 1024 1065ms >> 2048 7682ms >> 4096 21332ms > > hm, I'm not following you exactly -- what sql are you running? This > scales pretty well for me: > select array_dims(array(select generate_series(1,1000000))); > etc > > merlin > I have a C extension function that creates _int4 arrays of a specified size with random elements, in this case 128,256,512 etc. Another function from my extension returns the sum of the array. In this case I created a table with around 150k arrays to benchmark the extension. The query sums each array in the table and returns the 10 highest numbers. The C extension is actually a wrapper around the Eigen 3 template library, which works pretty well - now I am trying to tweak the input/output functions to get better performance with larger arrays. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
