[gdal-dev] In-memory VRT performance

[Even Rouault]

Hi Sean,

> 
> I have a GeoTIFF in S3 and am trying to access it via a VRT. I'm
> constructing the VRT in Python and then passing the string directly to GDAL
> like
> 
>     GDALOpenEx("<VRTDataset>...</VRTDataset>", ...)
> 
> I'm getting the results I expect, but very slowly. In my logs, it seems
> that GDAL is fetching the entire GeoTIFF and copying it to /vsimem/ before
> reading any data.

In your VRT, you use a filename starting by "http://", and this will be 
handled by the historic HTTP "driver", that downloads the whole file, before 
passing it to the final driver that can handle it.

You just need to prefix the filename with /vsicurl/

Even

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