[gdal-dev] Not writing PAM files

[Daniel Evans]

Hi David,

I'm familiar with the sort of behaviour Javier mentions from using QGIS.
Opening some file formats in read-only mode in QGIS (at least, I assume
that's what QGIS defaults to if I just view a raster!) will cause
"nuisance" .aux.xml sidecar files to be written with band statistics.

Cheers,
Daniel

On Mon, 3 Nov 2025, 14:20 David Klaus via gdal-dev, <
gdal-dev at lists.osgeo.org> wrote:

> Javier,
>
> That is strange. I could be wrong and maybe someone can weigh in if I am.
> But, I believe that aux files are created when you try to write information
> about or into the file that can't be stored within the file (for one reason
> or another). Are you trying to generate information about the file? Perhaps
> a code snippet would help everyone identify the issue?
>
> On Mon, Nov 3, 2025 at 9:12 AM Javier Jimenez Shaw <j1 at jimenezshaw.com>
> wrote:
>
>> Thank you David.
>>
>> Unfortunately I don't want to (a.k.a. cannot) change the original files.
>> I don't want to write any type of file in that directory (like the .aux.xml
>> files).
>>
>> (note: I am opening the files in C++ with GDALOpenEx)
>>
>>
>> On Mon, 3 Nov 2025 at 14:45, David Klaus <dklaus at carlsonsw.com> wrote:
>>
>>> Hi Javier,
>>>
>>> I'm not sure if this applies to your use case, but I ran into a similar
>>> issue embedding geolocation information in PDF files. Sidecar files were
>>> created, but the geolocation data wasn’t embedded directly in the PDF.
>>>
>>> At my company, we use the C++ GDAL API, and I was able to resolve it by
>>> opening the GDALDataset with the GDALAccess::GA_Update flag.
>>>
>>> As for whether GDAL reads sidecar files when present—I believe it does,
>>> but I'm not entirely certain, so I’ll defer to others on that point.
>>>
>>> Hope this helps,
>>>
>>>
>>> On Mon, Nov 3, 2025 at 4:13 AM Javier Jimenez Shaw via gdal-dev <
>>> gdal-dev at lists.osgeo.org> wrote:
>>>
>>>> Hi
>>>>
>>>> When I read some raster files (in particular thermal JPEG files), a
>>>> side car file .aux.xml appears next to it.
>>>>
>>>> I would like to avoid the creation of this side car file, but I want to
>>>> use any .aux.xml file if it is already there. Yes, I could imagine there is
>>>> a performance impact if I read it several times, but I am going to read the
>>>> file only once.
>>>>
>>>> The config option GDAL_PAM_ENABLED seems to be completely disabling PAM
>>>> functionality:
>>>>
>>>> https://gdal.org/en/stable/user/configoptions.html#persistent-auxiliary-metadata-pam-options
>>>> Reading the documentation, I would imagine that the PAM is completely
>>>> disabled, not only the creation of the side car file while reading a raster.
>>>>
>>>> Is it posible to not create the .aux.xml, but use it if present?
>>>>
>>>> Thank you
>>>> _______________________________________________
>>>> gdal-dev mailing list
>>>> gdal-dev at lists.osgeo.org
>>>> https://lists.osgeo.org/mailman/listinfo/gdal-dev
>>>>
>>>
>>>
>>> --
>>> David Klaus
>>> Carlson Software
>>>
>>>
>>> *Disclaimer*
>>>
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>>>
>>
>
> --
> David Klaus
> Carlson Software
>
>
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>
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