https://trac.osgeo.org/postgis/ticket/5854
> On Feb 24, 2025, at 10:22 AM, Paul Ramsey <pram...@cleverelephant.ca> wrote: > > Replicated. I had to go up to 430 to make mine flip behaviour, but it is > similar. > > P. > >> On Feb 24, 2025, at 9:46 AM, Frank Gevaerts <frank.gevae...@fks.be> wrote: >> >> Ok, I managed to simplify this to basically the example in the documentation: >> >> This works fine, in a reasonable (typically 100ms to 150ms) time: >> SELECT ST_Rotation(ST_Reskew(ST_AddBand(ST_MakeEmptyRaster(100, 359, 0, 0, >> 0.001, -0.001, 0, 0, 4269), '8BUI'::text, 1, 0), 0.0015)); >> >> This does not work fine, I stopped it after more than five minutes: >> SELECT ST_Rotation(ST_Reskew(ST_AddBand(ST_MakeEmptyRaster(100, 360, 0, 0, >> 0.001, -0.001, 0, 0, 4269), '8BUI'::text, 1, 0), 0.0015)); >> >> The only difference is the size of the raster, the broken one having just >> one more row. The postgres process was using 100% CPU during that time, I >> don't think it was doing any IO (so no tempfiles as far as I could see). >> >> I reproduced it on two systems, and things break for the same numbers, both >> on debian with postgresql 16, one with postgis 3.5.2/gdal 3.10.2, and one >> with postgis 3.4.2/gdal 3.2.2 >> >> Frank >> >> On Mon, Feb 24, 2025 at 07:49:07AM -0800, Paul Ramsey wrote: >>> If you provide a dump of a “good” raster, and a “bad” raster, and the exact >>> SQL you are running, the odds of someone duplicating your issue and then >>> fixing your issue go up 10-fold. I like fixing problems, not trying to >>> replicate problems. >>> ATB, >>> P >>> >>>> On Feb 24, 2025, at 7:38 AM, Frank Gevaerts <frank.gevae...@fks.be> wrote: >>>> >>>> Hello, >>>> >>>> I'm having issues with ST_Reskew(). The source raster (32BSI) contains >>>> 150000 points, and ST_Reskew() takes forever. If I rescale the raster to >>>> anywhere under ~80000 points, it suddenly only takes around 300ms. This is >>>> not linear, ~85000 points is bad, and then suddenly 80000 points is good. >>>> >>>> I'm not actually sure if it's "just" a performance problem or an infinite >>>> loop, I have not had the patience yet to have it run for more than 20 >>>> minutes. >>>> >>>> This is using postgis 3.5.2 on debian installed from apt.postgresql.org, >>>> and libgdal36 3.10.2 >>>> >>>> Is there anything I'm overlooking, or is there a memory usage parameter I >>>> can set to help with this? >>>> >>>> Frank >>> >> >> -- >> Frank Gevaerts frank.gevae...@fks.be >> fks bvba - Formal and Knowledge Systems http://www.fks.be/ >> Grote Baan 79 Tel: ++32-(0)11-21 49 11 >> B-3511 KURINGEN-HASSELT Fax: ++32-(0)11-22 04 19 >
