[postgis-users] St_dumpAsPolygons function is too slow

[Rémi Cura]

If you have a decently recent postgres,
you could maybe save time (at least it is more readable):


*SELECT dmp.geom, dmp.valFROM *
*my_raster a,  ST_DumpAsPolygons(a.raster) AS dmp*
CHeers,
Rémi-C

2015-07-20 15:28 GMT+02:00 Elmehdi OUADOUD <ouadoud.elmehdi at gmail.com>:

> For example:
>
> For a DEM raster X: 5261 Y: 4401 the vectorisation take 1 hour so I tintk
> that something is wrong on my querie
>
> Le lundi 20 juillet 2015 15:18:42 UTC+2, Paul Ramsey a écrit :
>>
>> I would expect the vectorization of a raster to be fairly slow.
>> Exactly how slow is another question.
>>
>> On Mon, Jul 20, 2015 at 6:14 AM, Elmehdi OUADOUD
>> <ouadoud... at gmail.com> wrote:
>> > Hi,
>> >
>> > I wonder know if the very very slow process is normal or i'm missing
>> > something?
>> >
>> > thanks in advance
>> >
>> > Le mercredi 15 juillet 2015 10:11:46 UTC+2, Elmehdi OUADOUD a écrit :
>> >>
>> >> Hi All,
>> >>
>> >> I want to transfom a raster data to polygons but the process is too
>> slow
>> >> it takes 35 minutes.
>> >> The querie i'm using :
>> >>
>> >>        select (ST_DumpAsPolygons(a.raster)).geom,
>> >> (ST_DumpAsPolygons(a.raster)).val
>> >>        from my_raster a
>> >>
>> >> Dimensions of my_raster
>> >>
>> >> X: 5261 Y: 4401
>> >>
>> >>
>> >> I'm missing something or it's normal ?
>> >>
>> >>
>> >
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>
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