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<p>Sean,</p>
<p>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</p>
<p>Even<br>
</p>
<div class="moz-cite-prefix">Le 19/04/2024 à 16:48, Sean Gillies via
gdal-dev a écrit :<br>
</div>
<blockquote type="cite"
cite="mid:CAOodmJpp1BUvmeRdt=fwFaG84Z9o0XozHqX8W9M1pwrxK0C2aQ@mail.gmail.com">
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<div>Happy Friday, folks!</div>
<div><br>
</div>
<div>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?</div>
<div><br>
</div>
<div>Thanks,<br>
</div>
<div><br>
<span class="gmail_signature_prefix">-- </span><br>
<div dir="ltr" class="gmail_signature"
data-smartmail="gmail_signature">Sean Gillies</div>
</div>
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<br>
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</blockquote>
<pre class="moz-signature" cols="72">--
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My software is free, but my time generally not.</pre>
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