[fdo-internals] PostGIS ticket 106 question

Wed Feb 20 13:07:52 EST 2008

Well, the FDO spec is fairly explicit in this case saying that the class must not have any instance data. It doesn't matter whether there is added metadata or not. If we made it depend on whether metadata existed or was determined by reverse engineering, then this operation would be somewhat unpredictable for a caller.

The FDO Delete command can be used to delete all objects of a class by not specifying a filter.

Thanks,
Orest.

-----Original Message-----
From: fdo-internals-bounces at lists.osgeo.org [mailto:fdo-internals-bounces at lists.osgeo.org] On Behalf Of Haris Kurtagic
Sent: Wednesday, February 20, 2008 1:17 PM
To: FDO Internals Mail List
Subject: RE: [fdo-internals] PostGIS ticket 106 question

I think it is not bug.
I believe differences in thinking come from difference that some
providers use metadata to describe FDO class some don't. In case when
provider uses metadata to describe FDO class then delete class could
have a differenet meaning than in case provider matches tables directly
to class.
If provider is not using metadata than there is nothing to do with
delete class command except to delete table. And considering consistency
of data etc. it is up to database to say if it is ok to delete not the
provider.

BTW: We don't have command do delete all data in FDO ? ( not counting
executing sql )

Haris

-----Original Message-----
From: fdo-internals-bounces at lists.osgeo.org
[mailto:fdo-internals-bounces at lists.osgeo.org] On Behalf Of Bruno Scott
Sent: Wednesday, February 20, 2008 6:19 PM
To: fdo-internals at lists.osgeo.org
Subject: RE: [fdo-internals] PostGIS ticket 106 question

So this meens that all these providers have a defect?
  Sdf
  Shp
  Autodesk Oracle
  King Oracle
  MySQL
  Autodesk SqlServer
Because they allow dropping table with data in it.
Bruno

Robert Fortin wrote:
>
> Oups!  Error...
>
> Correction: So as soon as there is data you ***can't*** delete the
> table...
>
> -----Original Message-----
> From: fdo-internals-bounces at lists.osgeo.org
> [mailto:fdo-internals-bounces at lists.osgeo.org] On Behalf Of Robert
Fortin
> Sent: Wednesday, February 20, 2008 11:42 AM
> To: FDO Internals Mail List
> Subject: RE: [fdo-internals] PostGIS ticket 106 question
>
> At first I thought that it was up to the provider to decide in what
> circumstance a class (table) could be deleted.
> Well, not really...
>
> The documentation is not always clear and detailed but in this case
the
> FDO spec for ApplySchema is pretty clear (extract from
> http://fdo.osgeo.org/files/fdo/docs/FDO_API/index.htm FdoIApplySchema
> Class Reference)
>
> If schema changes include deletion of classes or the schema itself,
then
> those classes (or the schema, if it is marked as deleted) must not
contain
> any instance data. If they do, an exception will be thrown.
>
> So as soon as there is data you can delete the table.  You must empty
the
> table before you can delete it.
>
> RF
>
> -----Original Message-----
> From: fdo-internals-bounces at lists.osgeo.org
> [mailto:fdo-internals-bounces at lists.osgeo.org] On Behalf Of Mateusz
Loskot
> Sent: Wednesday, February 20, 2008 11:22 AM
> To: FDO Internals Mail List
> Subject: Re: [fdo-internals] PostGIS ticket 106 question
>
> Bruno Scott wrote:
>> As we are about to fix that one
>>     http://trac.osgeo.org/fdo/ticket/106
>> Just want to check with you guys because there is a debate on that
one
>>
>>
http://www.nabble.com/Defects-in-PostGIS-provider-to12280094s18162.html#
a12295194
>>
>> For my point of view, as PostGIS allow dropping table with the SQL
"Drop
>> table" it's safe to do so.
>
> Bruno,
>
> It should be safe at least in current version of PostGIS provider,
> I mean where a feature class mapping to physical table is simple
> one-to-one relation, but if in future there is more complex mapping
> available then simple DROP TABLE may break data consistency.
>
> Cheers
> --
> Mateusz Loskot
> http://mateusz.loskot.net
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>

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