[postgis-users] multiline to linestring

[Gustavo Ces]

Thanks for answering, Dane!

    Reading my post you can see i don´t see clearly what i´m doing. ;)
What i want to do is to create a unique linestring from other linestrings, some of them sharing points. When line 1 and line 2 have both a common point, then i want a unique line as result. And when they don´t share a point, then two lines. So i was reading old list archives and i read about linemerge.
But linemerge seems to produce that multilinestring, and what i want are two linestrings. So i try to dump the multilinestring and then errors appear...
1) St_dump doesn´t exist as function, and i don´t know why ( maybe an old postgis version?).In Postgis manual:
"Availability: PostGIS 1.0.0RC1. Requires PostgreSQL 7.3 or higher." so, which is the problem?

2) if i try to dump(linemerge(collect(the_geom))) then :
ERROR: set-valued function called in context that cannot accept a set
Estado SQL:0A000

But if i try your sentence it works well, so the problem appears when you try to dump(linemerge(collect.... directly.
Which is the difference?

It works with your example but don´t know why...  :(


Gus





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