I'm working on an environment, where my C: directory is rather small. However by default, QGIS caches intermediate processing results there. Some processes are failing, due to size issues. I want to change the cache directory, but haven't found a clear setting to do so.
Under Network there is the option to configure a cache, but as I understand that does only apply for caching network data (e.g. WMS/WMTS data).
How can I change the processing cache under QGIS in windows?
After looking around a bit, I found out that the cache directory for me is:
C:\Users\hbh1\AppData\Local\Temp
I found this "read-only" in the QGIS environment settings:
This is set via environment variables and could be changed (system-wide) in your system environment variable dialog (Windows > System > Advanced System Settings). To change this only for QGIS, I used a custom variable - the dialog above the current environment variables.
Here I added two entries with D:\Users\hbh1\QGIS_cache ("TMP" and "TEMP", since both occurred) and restarted QGIS.
Since I had choosen a folder in which I needed admin rights to write, the first attempt failed with QGIS being unable to load projects (unzip the .qgz to the cache). Starting QGIS as an admin / changing the folder then solved this problem.
Since QGIS 3.32 you can also set this on a per-algorithm level, if you are using algorithms via Python this might be easy to always integrate:
