[postgis-users] newbie question about non closed rings

[Greg Williamson]

FWIW, Informix (and probably DB2's) spatial blade accepts invalid geometries -- you get a warning IIRC when it encounters one.

I'm in favor of being able to manipulate bad geometries in the database.

I've sometimes wondered if having a strict/non-strict option for each geometry column would make sense, with strict not allowing bad geoms. Then I could load into the non-strict and massge the shapes into a strict column.

But I don't think that's very good from a relational database aspect -- I can't think of any other data that would behave like that.

My $0.02 worth ...

Greg Williamson




----- Original Message ----
From: Mark Cave-Ayland <mark.cave-ayland at siriusit.co.uk>
To: PostGIS Users Discussion <postgis-users at postgis.refractions.net>
Sent: Friday, April 17, 2009 12:55:30 AM
Subject: Re: [postgis-users] newbie question about non closed rings

Paragon Corporation wrote:

> Mark Cave-Ayland,
> I forget were we planning on making this a switch option in later versions
> of PostGIS?  So that you could bring in polygons with unclosed rings and fix
> them in the db? 

Well the result of the earlier investigation showed that having a switch will just cause more problems than it will solve so this isn't going to work :(

I've always been a great believer in keeping the checking reasonably strict in an attempt to try and maintain the quality of geometries within the database, however recently there appears to be an increasing use cases on the list of people wanting to perform cleanup/processing directly in the database and it would be stupid to ignore this.

I think that if both Oracle Spatial and MS-SQL allow geometries to be stored with deformed features (i.e. incomplete rings) then I could be persuaded that the ERROR upon insertion should be downgraded to a WARNING instead. Would anyone like to check this behaviour and report back?


ATB,

Mark.

-- Mark Cave-Ayland - Senior Technical Architect
PostgreSQL - PostGIS
Sirius Corporation plc - control through freedom
http://www.siriusit.co.uk
t: +44 870 608 0063
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