ST_EstimatedExtent bug

[strk]

CREATE TABLE public.source (g GEOMETRY);
INSERT INTO public.source VALUES
 ('POINT(0 2047)'),
 ('POINT(0 0)'),
 ('POINT(2047 0)')
 ;
ANALYZE source;
SELECT ST_Extent(g) FROM source;
SELECT ST_Estimated_Extent('public', 'source', 'g');

Real extent: BOX(0 0,2047 2047) Estimated: BOX(-10.2349996566772 -10.2349996566772,2057.23510742188 2057.23510742188)

You can see it's not "just" a precision issue, but the minx and miny are off by 10 !

PostGIS 1.5 and 2.0 are immune.

The bogus one is POSTGIS="2.1.0beta3dev r11564"

[strk]

Paul, any idea ? I haven't touched the stats code except for hushing compiler warnings…

[darkblueb]

confirmed in test with

POSTGIS="2.1.0beta3dev r11494" GEOS="3.3.9dev-CAPI-1.7.9" PROJ="Rel. 4.8.0, 6 March 2012" LIBXML="2.8.0" }}}

[darkblueb]

observed in

POSTGIS="2.1.0beta3 r11567" GEOS="3.4.0dev-CAPI-1.8.0 r3823" PROJ="Rel. 4.8.0, 6 March 2012" GDAL="GDAL 1.10.0, released 2013/04/13" LIBXML="2.8.0" LIBJSON="UNKNOWN" RASTER

[pramsey]

Here's the issue:

http://trac.osgeo.org/postgis/browser/trunk/postgis/gserialized_estimate.c#L1416

The thing is, removing this will open other problems, since this was added precisely because edge cases were being lost. At the end of the day, the "estimated" box is 1% larger than the sampled box, which is *itself* smaller than the *actual* box, since… it's a *sample*! The key word here is "estimated". I incline towards leaving thing as they are.

[strk]

I don't think it's important for "estimated" bounding box to be larger than the actual one. It's important that it is "about the same as the actual one", based on a sample. If the sample is the whole set, I'd expect the estimated extent to also be the one of the whole set. That's how it worked up to 2.0. Do you have a case for that 1% enlargement ?

[robe]

Can I push this forward? to 2.1.1 or you expecting to do something with this like SOON.

[robe]

strk pramsey said he doesn't want to bother. Change back if YOU plan to do something about it. Why is this even marked as a blocker?