[postgis-users] st_union

[Paul Ramsey]

On Mon, Mar 2, 2020 at 1:16 PM Alexandre Neto <senhor.neto at gmail.com> wrote:
>
> Stating the obvious,
>
> Do you have a spatial index on your geom column?

That will make no difference, the query is reading the whole contents
of the column, a spatial index will do nothing.

P


>
> Alexandre Neto
>
> A segunda, 2/03/2020, 17:04, Paul Ramsey <pramsey at cleverelephant.ca> escreveu:
>>
>> No, if it’s returning the answer you want, that’s the way to do it, and there’s no way around it.
>>
>> > On Mar 2, 2020, at 6:25 AM, <paul.malm at lfv.se> <paul.malm at lfv.se> wrote:
>> >
>> > Hi list,
>> > I would like to do this:
>> > CREATE TABLE public."Areas_union" AS select  (st_dump(st_union("the_geom"))).geom from "Areas";
>> >
>> > But it takes such a long time to execute, is there a smarter way to do it?
>> >
>> > Kind regards,
>> > Paul
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