As mentioned previously, PgRaster support in GeoServer is not there yet. This is good, because we can learn how to consume it ourselves!
Let's import some data first:
raster2pgsql -s 4326 -C -l 2,4,6,8,10,12,14 -I -F -t 256x256 NE2_HR_LC_SR_W_DR.tif webgis.ne_raster | psql -h localhost -p 5434 -U postgres -d mastering_postgisIn Chapter 5, Exporting Spatial Data, we used PostgreSQL's large object support to export the raster from the database. We will now build on what we achieved there, so we can come up with a simple raster extractor query for our WMS handler. The interesting bit is the query we used for assembling the tiles of the imported raster back into one raster:
select ST_Union(rast) as rast from data_import.gray_50m_partial where filename = 'gray_50m_partial_bl.tif'
Our slightly extended query looks like this:
select --3. union our empty canvas with the extracted raster ST_Union(rast) as rast from ( ...