Hi Saber,
Thank you for your feedback. You are an expert on the subject and I
really appreciate your comments.
Postgresql is probably not the best option in terms of performance. But
it is a practical solution to centralize all information in a single place.
I'm using postgis raster support, for example, which is not faster than
files, but it is ok for my use cases. I have all the spatial data in one
place, where I can manage authentication and authorizations quite well.
The end user will use a cached WMTS/TMS service (MapProxy on top of QGIS
Server), and the performance will be ok. I want to use QGIS Server to
provide data in netCDF files as temporal layers. The end user will use
cached data and will not notice any performance issues. The cache can be
created once, since the data is always in the past. That's my use case:
I'm not processing the data or making any processing. Just providing
maps/tiles.
GDAL and QGIS works very well with Postgresql and users are familiar
with Postgresql (setup and usage).
How difficult would be to have netCDF data in Postgresql?
1) We should have a way to store the data (and metadata) on the database
(like we do with rasters, with raster2pgsql).
2) We need to improve QgsMeshLayer to read from a PG uri, like:
uri_config = {
'service':'atlantico',
'schema':'public',
'table':'az1_hs_2023101200_03',
'geometrycolumn':'rast'
}
uri_config = {key:val for key, val in uri_config.items() if val is not None}
md = QgsProviderRegistry.instance().providerMetadata('mdal')
uri = QgsDataSourceUri(md.encodeUri(uri_config))
mesh_layer = QgsMeshLayer(uri.uri(False), "layer_name", "mdal")
If you think this does not make sense, you are probably right :-) I'm
quite new to netCDF data and I just want to use the tools I'm used to
have with this format.
Regards,
Jorge
On 14/12/23 10:13, Saber Razmjooei wrote:
Hi Jorge,
What is your motivation for storing mesh data in PG? If you want to
have fast access to large central datasets, PG is probably not a good
storage option. Best to investigate Zarr (https://zarr.dev/) which is
a cloud optimised format for large multidimensional datasets. We need
to first implement it in MDAL for QGIS to be able to load the data
effectively.
Another option to serve large NetCDF/GRIB data is to set up an EDR
(https://ogcapi.ogc.org/edr/overview.html) service which we are adding
support for it in QGIS.
Kind regards
Saber
On Wed, 13 Dec 2023 at 19:36, Jorge Gustavo Rocha via QGIS-User
<qgis-user@lists.osgeo.org> wrote:
Hi,
I'm playing with netCDF files. I add them to QGIS using the mdal
provider (mesh layer). Reading netCDF data from files works very well.
My question is: is it possible to read netCDF data from
Postgis/Postgresql?
I can store netCDF files in Postgis using raster2pgsql, but the
data is
stored as raster and I can only open it as raster in QGIS and not as
mesh. Is works, but not as good as the mesh support.
I'm storing it, using something like this:
raster2pgsql -s 4326 -d -I -C -M AZ1_HS_2023101200.nc -F
public.az1_hs_2023101200 | psql service=atlantico
Thanks in advance,
Jorge Gustavo
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--
Saber Razmjooei
www.lutraconsulting.co.uk <http://www.lutraconsulting.co.uk>
+44 (0)7568 129733
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