Opening a remote ZARR dataset is very slow #63153
Description
What is the bug or the crash?
If you try to open a remote ZARR dataset in QGIS (e.g. through data sources manager), QGIS may freeze for an extended period of time (e.g. more than a minute) before opening the dialog with the list of sub-layers (arrays) as provided by GDAL.
It seems the problem is in QgsGdalProvider::sublayerDetails() which may try to open every single array within ZARR dataset to get some extra metadata - this was added in #57146. When I disable code added in that pull request, the dialog opens nearly instantly.
Steps to reproduce the issue
- open data sources manager, go to Raster tab
- copy the following into the raster dataset line edit box:
ZARR:"/vsicurl/https://objects.eodc.eu/e05ab01a9d56408d82ac32d69a5aae2a:202506-s02msil2a/10/products/cpm_v256/S2C_MSIL2A_20250610T103641_N0511_R008_T32UMD_20250610T132001.zarr"
- click Add button - QGIS will freeze and it will take a while until it opens the sublayers dialog to pick some arrays to load.
Versions
QGIS master
Supported QGIS version
- I'm running a supported QGIS version according to the roadmap.
New profile
- I tried with a new QGIS profile
Additional context
No response