[QGIS-Developer] Status of transaction support in Geopackages

[Mark Johnson]

>> Do you have a link to the issues? Does it ignore them or worse?

The original report was 3 years ago and is still active:

https://issues.qgis.org/issues/12479

It was also a topic of a QGIS Grant Applications - August 2016
'Correction of QgsOgrProvider implementaion of GDAL 2.0'

A pull request was offered about Oct/Nov 2016 for Qgis 2.18 so that the
corrected code would be used for the start of Qgis 3.0 - but refused
because it was considered an api change.

Around April 2017 I saw that in Qgis 3.0 had still not been corrected,
despite the many changes that had been made.

Up to then I had been using a gdal version adapted to support writable
SpatialViews, that had not been accepted by gdal. But due to the evolvement
of gdal was becoming to difficult to maintain.

Around June I started work on the Spatialite-Provider, with consultations
with Alessandro Furieri (Sandro) of the Spatialite project about the future
needs, of what is now being termed, as Spatialite 5.0.

>> Having you all on the same code base is a neat solution I think.
Not when the 1 Provider (Ogr) will only offer partial results.
Writable SpatialView has existed since Spatialite 2.4 (we now have 4.3) and
there is no sign that Ogr will support this in the near future.

With Spatialite 5.0, where the world of Vector/Rasters, with Se/Sld Styles
are being brought togeather, this will become more difficult to deal with
with the separated gdal/ogr providers for all aspects of what can be done.

>> the amount of work to review the massive PRs was a limiting factor to
have that merged.
>> Do you have plans to ease that review process?
At the moment I am completing the last stage (of originally 4 stages) of
development (Database Maintenance, adding/renaming of columns etc.).

I have also started work on a Pdf which should help as an orientation as to
what the changes are and the reasons why.
One point I wrote this morning is: 'The Spatialite 5.0 Layout is similar in
nature to WMS/WFS 'getCapabilities', combining Vector, Raster and
Se/Sld-Styles.'

One goal is that such a Pdf should assist any reviewer who is willing to
work through this.

A major problem is also, that since Spatialite 5 has not yet been release,
it is difficult to understand why these massive changes are needed. So the
reluctance it is no surprise to me.

But the facts remain:
a) The present Spatialite-Provider is better than the Ogr support for
Spatialite
b) The present Spatialite-Provider will not be able deal will with what
Spatialite 5 offers

Although I myself am not a co-developer of Spatialite (more like a
collaborator), I intend to keep this up to-date with future developments.
It is also likely that Sandro will take a closer look after the present
development phase is over.

Mark Johnson, Berlin Germany
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