Questions tagged [st-union]

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4 votes
1 answer

Unsplitting/merging lines that have coincident endpoints using PostGIS

I have a large dataset of lines/linestrings (ie. a road network), which is unregularly segmentised/ split and the lines needs to be merged at coincident endpoints (if only two lines are touching). I'd ...
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  • 153
5 votes
1 answer

Counting geometries which intersect another geometry using PostGIS

I'm trying to calculate the total area for each layer I have within a specific area and count the geometries which intersects with that specific area. I can calculate the area and the results seem ...
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  • 391
2 votes
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Virtual layers w/ spatial query not working as before (3.18.1 vs 3.20.3)

I have a set of maps that intensively utilizes virtual layers, but last week our boss updated from QGis 3.10/3.18 to 3.20.3 in all PCs, and now the layers are not loading. Normally they would refresh ...
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  • 333
0 votes
1 answer

Using ST_Union to aggregate polygon parts resulting of ST_SubDivide leads to a GEOS TopologyException

Follow up on this topic: Optimizing an intersection between a single massive multipolygon (WKT) and many features from PostGIS I noticed I have to run an ANALYZE (not VACUUM ANALYZE!) on the table for ...
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