my question concerns the use and performance of several software tools in conjunction, namely PostgreSQL, PostGIS, QGIS, and GDAL.
I'm a long-time ArcGIS, Python, and R user who is interested in diversifying into the free open source GIS ecosystem and Linux as well. Recently I've been very interested in using QGIS (ver 2.8) together with PostgreSQL (ver 9.4) and PostGIS (ver 2.1), and I've installed the software on a computer with Windows 8.1 x64 (the computer specs in brief: ThinkPad X200s with a 2.1GHz Core 2, 8GB RAM, and a 240GB SSD). Once I learn how to manage my spatial data (~100GB worth), I'd like to run Ubuntu on this machine.
At the moment, I'm simply trying to reliably store and retrieve shapefiles and rasters. So far I've been successful in loading shapefiles into PostGIS, but rasters are proving more problematic. I have successfully completed single and batch imports of small geoTIFF and GRID files, but larger rasters (say, a 15619x14655 cell IMG or TIFF file 870MB in size on disk) take forever to load into PostGIS. I've read and configured the raster2pgsql tool to build spatial indices and load rasters by tiles using these parameters:
raster2pgsql -s 3161 -C -I D:\PostGIS_data\dem.img -t auto raster.dem | psql -h localhost -U postgres -p 5432 -d postgresPerformance in importing is still very poor, and the hardware is not the problem. Visualisation of PostGIS rasters in QGIS is even worse, slowly loading small rasters at best or freezing altogether. Large rasters like the one I mentioned are impossible to visualise in QGIS. From the documentation and forum discussions, this shortcoming appears to be due to GDAL's PostGIS raster driver and not QGIS itself. Forum discussions mention this problem briefly and some even suggest that rasters shouldn't be stored in PostGIS (what is the point in a spatial database that doesn't handle rasters smoothly?). Yet I routinely use ESRI's file geodatabase to store, visualise, and analyse quite large (~70GB) rasters quickly and easily, and ArcGIS 10.1 never freezes or slows due to such routine operations. These performance roadblocks are disappointing and leave me unimpressed with FOSS GIS.
Is there something I'm missing here, a bottleneck I haven't addressed? Does PostgreSQL need tuning to realise the performance benefits of PostGIS? Am I missing a version of GDAL that I need to hunt down and compile? How do I improve PostGIS performance and visualisation in QGIS of shapefiles and rasters especially? How can I enjoy the glory of comprehensive and speedy spatial data management via a Linux terminal?Any help on this issue would be welcome!
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I'm a long-time ArcGIS, Python, and R user who is interested in diversifying into the free open source GIS ecosystem and Linux as well. Recently I've been very interested in using QGIS (ver 2.8) together with PostgreSQL (ver 9.4) and PostGIS (ver 2.1), and I've installed the software on a computer with Windows 8.1 x64 (the computer specs in brief: ThinkPad X200s with a 2.1GHz Core 2, 8GB RAM, and a 240GB SSD). Once I learn how to manage my spatial data (~100GB worth), I'd like to run Ubuntu on this machine.
At the moment, I'm simply trying to reliably store and retrieve shapefiles and rasters. So far I've been successful in loading shapefiles into PostGIS, but rasters are proving more problematic. I have successfully completed single and batch imports of small geoTIFF and GRID files, but larger rasters (say, a 15619x14655 cell IMG or TIFF file 870MB in size on disk) take forever to load into PostGIS. I've read and configured the raster2pgsql tool to build spatial indices and load rasters by tiles using these parameters:
raster2pgsql -s 3161 -C -I D:\PostGIS_data\dem.img -t auto raster.dem | psql -h localhost -U postgres -p 5432 -d postgresPerformance in importing is still very poor, and the hardware is not the problem. Visualisation of PostGIS rasters in QGIS is even worse, slowly loading small rasters at best or freezing altogether. Large rasters like the one I mentioned are impossible to visualise in QGIS. From the documentation and forum discussions, this shortcoming appears to be due to GDAL's PostGIS raster driver and not QGIS itself. Forum discussions mention this problem briefly and some even suggest that rasters shouldn't be stored in PostGIS (what is the point in a spatial database that doesn't handle rasters smoothly?). Yet I routinely use ESRI's file geodatabase to store, visualise, and analyse quite large (~70GB) rasters quickly and easily, and ArcGIS 10.1 never freezes or slows due to such routine operations. These performance roadblocks are disappointing and leave me unimpressed with FOSS GIS.
Is there something I'm missing here, a bottleneck I haven't addressed? Does PostgreSQL need tuning to realise the performance benefits of PostGIS? Am I missing a version of GDAL that I need to hunt down and compile? How do I improve PostGIS performance and visualisation in QGIS of shapefiles and rasters especially? How can I enjoy the glory of comprehensive and speedy spatial data management via a Linux terminal?Any help on this issue would be welcome!
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