Delete duplicate polygon nodes with PostGIS

Question

I'm trying to delete duplicate nodes from a shapefile with QGIS, but after running the tool to delete it, nothing happens and shows the same errors.

I thought that maybe importing to postgis could be easier. What I want to do is:

1. Extract points from polygon (this is already done)

2. Delete the duplicate points ¿with st_equals?

3. To finish, reshape the points to polygons without the duplicate points.

Anyone know if this methodology would be ok? I can do the first and second steps, but don't know if number 3 is possible, or if there is a better alternative.

Any clue or suggestion?

• user30184: It may be as easy as to simplify with zero tolerance. At least worth a try.
• radouxju: be careful that there is a mandatory duplicate node at the start/end of the drawing. Removing one of those points could corrupt your data. I recommend that you use simplify with a diminutive tolerance, as suggested by @user30184
• Pablo Pardo: you are right. st_simplify(geom,0) is the best solution. Thanks

Answer 1

If you are running PostGIS 2.0+, you can use the ST_RemoveRepeatedPoints function, so no need to go thru all that trouble of extracting and reconstituting

http://postgis.net/docs/manual-2.1/ST_RemoveRepeatedPoints.html

UPDATE yourpolygontable SET geom = ST_RemoveRepeatedPoints(geom);