Hi,

I ran into same problems when dealing with a few thousand files.  The idea was 
to load the very small shp files created by another process and then merge 
then.  I solved the problem by loading and merge it then I SAGA.  It generally 
loads everything into memory and probably does not keep a file handle once the 
file are open.  I believe this issue is created by Windows and not QGIS.  I 
remember being told to go on Linux as this maximum operating system file max 
can be modified with a script.

Nicolas

> Le 18 nov. 2019 à 04:59, Jésahel Benoist <[email protected]> a écrit :
> 
> From my experience, GeoTIFF has a long history and is a more
> appropriate format to handle multiple large rasters. As a container,
> it could handle misc compression format (JPEG an other), misc
> representation at different scales (resolution is not a problem), misc
> color modes with raster/vectorial alpha layer, and so on. In one of my
> projects I handle more than 400 raster files (4000x4000x32) without
> any problem.
> Of course, a better and final choice would be to tile everything, but
> it is sometimes difficult with older maps.
> 
>> Le lun. 18 nov. 2019 à 10:12, Patrick Dunford
>> <[email protected]> a écrit :
>> 
>> Good day to all
>> 
>> One of the user experiences I have had from using the Qgis software has been 
>> with projects using large numbers of raster tile layers. These layers are 
>> generally tiles that have a size of 4800x7200 pixels in GeoJPEG format and 
>> have either been downloaded directly from tile servers to these locally 
>> stored files, or created from downloaded tiles with other layers overlaid in 
>> Gimp projects.
>> 
>> There appears to be some architectural limit in Qgis desktop software 
>> relating to either the total number of raster layer [files] in a project or 
>> to the total number of pixels in raster layer [files] in a project. This is 
>> unrelated to the number of layers or pixels currently enabled for display in 
>> the map canvas. In practice, the appearance of this limit is that it is 
>> kicking in long before the host computer's own physical resources are 
>> anywhere near fully engaged. Map digitising and editing is done on systems 
>> with 32 GB of physical memory (RAM) and 200 GB of SSD-based virtual memory 
>> (swap) and these systems are able to edit very large Gimp projects for user 
>> tile creation that often engage all of the system's physical memory and 
>> around 100 GB of the virtual memory without problems. But these types of 
>> numbers are in practice never seen with Qgis projects when the raster layer 
>> limit is being seen.
>> 
>> The appearance of a raster layer limit is generally experienced in older 
>> versions of the software by layers being displayed on the canvas as garbage, 
>> and in newer versions by the software crashing. It will only start working 
>> again if raster layers are removed from the project. However, when layers 
>> are loaded from WMTS servers, no appe
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