[fdo-internals] SQLite provider issues

[Romica Dascalescu]

Hi Haris,

1) SetIsComputed(), there is a thin line here since a view is a computed/generated class. Why this would be a problems in this case?

2) You can say this is a limitation of the provider and we cannot update views. However there is a way to update a view if Id of the view and geometry is from the same class and those are defined in (fdo) metadata (but this is in FDO 3.6 only).
All the time SupporsWrite()=false for views and I don't see a problems since the provider is not meant to implement everything.

SupporsWrite() will be false in case tythe file is read only and all classes will have this flag set to false. This flag should be checked by the application and take care of this otherwise exception will be thrown but only later at execute time.

SQLite provider do not enforce too many things (starting with string length and ending with read-only flag), and in case an application ignore this flag and use a SQL commands to update database there is nothing provider will do, since provider will not parse the SQL! The sqlite engine for sure will throw an exception at execution time.

Thanks,
Romy.

-----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, July 28, 2010 9:25 AM
To: FDO Internals Mail List
Subject: [fdo-internals] SQLite provider issues

Hi,

FDO Sqlite provider has changed in revision 4823 ( from 3.4 to 3.5 )
regarding views in sqlite.

I think it introduced two issues:

1. Provider will mark fdo class generated from view as computed
"SetIsComputed(true)" which is wrong by fdo definition of computed
class.

2. SupportsWrite is set to false - which is wrong. SQlite suports
write to views when they have "instead of" trigger


Also there is yet another problem of understanding what SupporsWrite
means in FDO.
Is it just informative or will enforce it.
Right now, sqlite provider will pass trough update commands to sqlite
even if provider marked some class as "doesn't support write".
I think if class is marked as non-writable by provider shouldn't send
update commands to underlaying storage.

Haris
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