What is this misterious calculation that can't be performed with any version of MapAlgebra?
> -----Original Message----- > From: [email protected] [mailto:postgis-users- > [email protected]] On Behalf Of Miguel-Angel Manso-Callejo (UPM) > Sent: Friday, September 27, 2013 2:25 AM > To: [email protected] > Subject: [postgis-users] About 2-dimensional arrays of postgresql > > Dear all, > > I'm writing a stored procedure (pgplSQL) that uses postgis functions > version 2.1 > Dump the contents of an image on a two-dimensional array and then I > update the cells according to some calculations. > The process is slow, but after a while I discovered devote to the problem, or > the slowness is due to operations that read and update the two- > dimensional array. > > The code is roughly this: > > DECLARE > .. > img double precision [] []; > > i integer j integer; > > BEGIN > > select ST_DumpValues (rast, 1, false) INTO img from .. > > for i IN 1 .. 1000 LOOP > for j IN 1 .. 500 LOOP > ........ > img [i] [j]: = ..............; > END LOOP; > END LOOP; > > select ST_SetValues (image, 1, 1, 1, img) INTO imagen2; > .... > END; > > Anyone know why the update of the values of the two-dimensional array is > slow?, Poorly defined array for the type of operations performed? > > thank you very much > Best regards. > > Miguel A. Manso _______________________________________________ postgis-users mailing list [email protected] http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
