[gdal-dev] Block cache and VRT sources

[Even Rouault]

Sean,

Within a given GDALDataset opened on a VRT, if the VRT references 
several times the same source, only one GDALDataset will be opened for 
it, so you may benefit from the block cache mechanism (if it is 
triggered. VRTSource::IRasterIO() calls IRasterIO() on the source band, 
which doesn't necessarily always trigger block-based reading).  But if 
you open another VRT (or the same one), it will not share the same 
GDALDataset for sources that may be common with the first one, so no 
re-use of existing block cache. For network sources, the I/O cache at 
the /vsicurl/ level works however on filenames, not VSIFILE* instances, 
so you will save network reads

Even

Le 19/04/2024 à 16:48, Sean Gillies via gdal-dev a écrit :
> Happy Friday, folks!
>
> Are the source rasters of a VRT added to the block cache such that 
> different VRTs using the same source can avoid reads from disk or the 
> network? Or is it intended that the VSI cache covers this need instead?
>
> Thanks,
>
> -- 
> Sean Gillies
>
> _______________________________________________
> gdal-dev mailing list
> gdal-dev at lists.osgeo.org
> https://lists.osgeo.org/mailman/listinfo/gdal-dev

-- 
http://www.spatialys.com
My software is free, but my time generally not.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/gdal-dev/attachments/20240419/60892224/attachment.htm>