Combining Polygons

[Paul Ramsey]

In postgis,

select geomunion(the_geom) from the_table group by the_categorical_attribute

Paul

Dylan Beaudette wrote:

> Actually, I would be interested in knowing if there is some way to do with
> opensource software, what the ESRI world calls a "Dissolve". i.e. merge all
> contiguous polygons with a common key into a single polygon...
>
> any ideas?
>
> Thanks,
>
> Dylan
>
> On Tuesday 19 October 2004 02:32 pm, Eric Katherman wrote:
>
>>Please disregard this, although it would be a nice thing to know, my speed
>>problem was solved with the previous post (Speeding Up Queries).
>>
>>Thanks Paul!
>>
>>Eric
>>
>>
>>>As a possible solution to my previous speed post, it would seem to make
>>>sense if I could take say all of the parcels in one city block area and
>>>combine them into one parcel.  Does anybody have a suggestion as to how I
>>>could approach that, the adjacent polygons surely have some common "key"
>>>which could be used.
>>>
>>>Eric