[QGIS-Developer] Question on FGDB support for "Save As" / "Export"

[Nyall Dawson]

On Tue, 31 Jul 2018 at 20:06, Andreas Neumann <a.neumann at carto.net> wrote:

>
> About issue 2:
>
> @Jürgen: can you include the necessary gdal-filegdb package also in the standalone installer - or are there license problems?
>

-1 to packaging the gdal-filegdb package by default. My rationale:

- I've experienced lots of issues with this driver. For one, it's much
slower to open gdbs, especially over networks. I've also hit bugs in
the past where the driver doesn't handle certain subset queries in the
same way as other ogr drivers (I can't recall the exact details, but I
think the particular issue I hit was fixed.)

- The driver has known issues. From
https://www.gdal.org/drv_filegdb.html, there's e.g. this important
one: "The SDK is known to be unable to open layers with particular
spatial reference systems.". And then on
https://www.gdal.org/drv_openfilegdb.html there's a list of features
that we'd lose by changing to the filegdb driver:

"Advantages of the OpenFileGDB driver:

Can read ArcGIS 9.X Geodatabases, and not only 10 or above.
Can open layers with any spatial reference system.
Thread-safe (i.e. datasources can be processed in parallel).
Uses the VSI Virtual File API, enabling the user to read a Geodatabase
in a ZIP file or stored on a HTTP server.
Faster on databases with a big number of fields.
Does not depend on a third-party library.
Robust against corrupted Geodatabase files.

Drawbacks of the OpenFileGDB driver:

Read-only.
Cannot use spatial indexes.
Cannot read data from compressed data in CDF format (Compressed Data Format)."

That's a pretty significant loss in my opinion - especially the point
about the closed source driver being non thread-safe.

- The OpenFileGDB driver is very heavily tested for robustness and
security issues with the ongoing fuzz testing of GDAL drivers.

- Last, but not least, we'd lose the ability to actually fix issues.
We'd be dependent on bug fixes in the ESRI SDK, and be powerless to
get fixes we need implemented.


These are all significant issues, and the moment we make the switch to
the closed source driver and give users write support, there's no way
we can revert this decision and remove the ability to edit GDB files.
It's not a decision we can make lightly.

I'd rather leave this decision up to individual users (and those who
make in-house software packages for deployment in their organisation)
to make. I.e. leave it as is, where it's effectively an "opt-in"
change. And push people to helping make the open driver better, as
it's a more sustainable solution in the long term.

(Lastly, a rant: I hate file geodatabases. They are the WORST format
for spatial data that I've seen. It's like ESRI took everything which
people disliked about shapefiles and magnified those. Instead of a
handful of files, we get hundreds. Instead of minor user confusion
about how they need to package all the dependent files, we get this
super-confusing folder/file mix, which causes all sorts of issues for
non-ArcGIS software because it just breaks fundamental file management
assumptions. And they are SLOW. So SLOOOOOOW. Even in ArcGIS they are
slow to open and manage. GIve me shapefiles over this monstrosity any
day.)

Nyall