[postgis-users] Vacuum analyse ERROR: Operationon twoGEOMETRIESwith different SRIDs

[Mark Cave-Ayland]

> -----Original Message-----
> From: postgis-users-bounces at postgis.refractions.net 
> [mailto:postgis-users-bounces at postgis.refractions.net] On 
> Behalf Of Markus Schaber
> Sent: 20 June 2005 09:04
> To: PostGIS Users Discussion
> Subject: Re: [postgis-users] Vacuum analyse ERROR: 
> Operationon twoGEOMETRIESwith different SRIDs

Hi Markus,

> Mark Cave-Ayland wrote:
> 
> > Having mixed SRID geometries in a column is, of course, completely 
> > non-sensical since the results of any spatial query could 
> be invalid.
> 
> I don't think so, I can imagine several possible uses of 
> mixing SRIDs in the same column.
> 
> One could query by other columns, and get the resulted 
> geometry. Or have two columns, one containing the original 
> geometry as received from outside with whatever SRID they 
> use, and the second one containing the WGS84 representation.

OK that's a fair enough use case...

> I do not know whether we really are in the position to tell 
> users that this is all nonsense.

Yeah I did point out that it was a personal opinion in one of my posts. I
tend to write applications that are very strict, and as a result I prefer
something that breaks on me than on a user out in the field. I would still
be tempted to code it using a view, just so that it would help indicate to
other developers that the column has no spatial meaning...

> We are in the position to tell them that this is currently 
> not supported, however :-)
> 
> Maybe the best short-term solution would be to forbid the 
> generation of indices on mixed SRID columns, but make ANALYZE 
> stable enough to cope with everything it stumbles over.

Going forward this shouldn't be a problem, as from 8.0 we control the
ANALYZE anyway :) I was just a little concerned that we have to drop SRID
checks on *some* operators just to get ANALYZE to work on earlier PG
versions :(


Kind regards,

Mark.

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