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
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