[postgis-users] union/merge huge river dataset into single lines group by name

karsten vennemann karsten at terragis.net
Mon Aug 31 13:20:26 PDT 2009

PostGIS users,
I was researching how to effectively merge river segments in a really huge river dataset that have the same name and touch each other (share a coordinate). The resulting layers should be used for labeling purposes. I found that I could use something along the lines of ST_LineMerge(ST_Collect(the_geom)) but would anybody have an example how a merge operation would look to merge by river name and only if the segments touch ?
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