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<p>You could put Zarr into a ZIP. But there's little point in using
SOZip for that use case (SOZIP has been merged into master 6
months ago by the way, in GDAL 3.7.0), since SOZip is for
compressing large files. In a Zarr archive, you would have a lot
of small/medium sized files for each chunk/tile. And when you need
to read one, you read it in its whole (where SOZip aim is to be
able to read efficiently a subset of a compressed file). SOZip
main use case is more for vector datasets (geopackage, flatgeobuf,
potentially Esri file geodatabase...)<br>
</p>
<p>For Zarr in ZIP, you should either use uncompressed Zarr and use
Zip deflate compression, or compressed Zarr (blosc, whatever) and
use uncompressed Zip ("store method"). If you have a Zarr dataset
with lots of tiles, it might actually be relevant to use the
zipindex (<a class="moz-txt-link-freetext" href="https://github.com/minio/zipindex">https://github.com/minio/zipindex</a>) extension to locate
more quickly each Zarr chunk, but GDAL won't make use of it.<br>
</p>
<div class="moz-cite-prefix">Le 08/12/2023 à 21:23, Meyer, Jesse R.
(GSFC-618.0)[SCIENCE SYSTEMS AND APPLICATIONS INC] via gdal-dev a
écrit :<br>
</div>
<blockquote type="cite"
cite="mid:47772BA8-4754-4DF1-98F6-96BB6F995069@ndc.nasa.gov">
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<p class="MsoNormal">The underlying network file system is
opaque to us and can change on occasion. But recently our
team were asked to cull unused files due to inode counts.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">We’re excited to explore SOZip on our
vector data where random seek is important to us, but we’re
waiting for that branch to be merged into master. I don’t
trust standard zip libraries to be performant for this usage
case but I’m willing to be shown otherwise.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Jesse<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<div
style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span
style="font-size:12.0pt;color:black">From: </span></b><span
style="font-size:12.0pt;color:black">gdal-dev
<a class="moz-txt-link-rfc2396E" href="mailto:gdal-dev-bounces@lists.osgeo.org"><gdal-dev-bounces@lists.osgeo.org></a> on behalf of
Laurențiu Nicola via gdal-dev
<a class="moz-txt-link-rfc2396E" href="mailto:gdal-dev@lists.osgeo.org"><gdal-dev@lists.osgeo.org></a><br>
<b>Reply-To: </b>Laurențiu Nicola <a class="moz-txt-link-rfc2396E" href="mailto:lnicola@dend.ro"><lnicola@dend.ro></a><br>
<b>Date: </b>Friday, December 8, 2023 at 3:01 PM<br>
<b>To: </b>gdallists <a class="moz-txt-link-rfc2396E" href="mailto:gdal-dev@lists.osgeo.org"><gdal-dev@lists.osgeo.org></a><br>
<b>Subject: </b>[EXTERNAL] [BULK] Re: [gdal-dev] GTiff
bit shuffle compression feature request<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
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Use the "Report Message" button to report suspicious
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<p class="MsoNormal" style="margin-bottom:12.0pt"><br>
<br>
<o:p></o:p></p>
<div>
<div>
<p class="MsoNormal"><span
style="font-family:"Arial",sans-serif">On Fri,
Dec 8, 2023, at 21:32, Even Rouault wrote:<o:p></o:p></span></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt"
id="qt">
<p>yes, poor wording of mine. I meant that if using
PREDICTOR=3, one should compare with FILTER=DELTA. But
looking more closely, they are not strictly equivalent.
PREDICTOR=3 applies the delta as b[0]-a[0], b[1]-a[1],
b[2]-a[2], b[3]-a[3] where a[0...3] and b[0...3] are seen
as the 4 byte representation of the float32, whereas
FILTER=DELTA does the difference b_float - a_float as
floating point. This isn't the same...<o:p></o:p></p>
</blockquote>
<div>
<p class="MsoNormal"><span
style="font-family:"Arial",sans-serif"><a
href="https://www.blosc.org/posts/bytedelta-enhance-compression-toolset/"
moz-do-not-send="true" class="moz-txt-link-freetext">https://www.blosc.org/posts/bytedelta-enhance-compression-toolset/</a>
seems to be the equivalent.<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-family:"Arial",sans-serif">>
inode allocation<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-family:"Arial",sans-serif">XFS or
ZIP?<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-family:"Arial",sans-serif">>
extra step to decompress Zarr out of ZIP<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-family:"Arial",sans-serif">Most
libraries should be able to read Zarr directly from a
ZIP archive.<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
</div>
</div>
</div>
<br>
<fieldset class="moz-mime-attachment-header"></fieldset>
<pre class="moz-quote-pre" wrap="">_______________________________________________
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</pre>
</blockquote>
<pre class="moz-signature" cols="72">--
<a class="moz-txt-link-freetext" href="http://www.spatialys.com">http://www.spatialys.com</a>
My software is free, but my time generally not.</pre>
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