I've successfully loaded a geoTif into PostGIS (Postgresql 9.3.9) using the following command on my Ubuntu 14.04 server:-
sudo -u postgres raster2pgsql -s 4326 -d -I -C -M -R -l 4 /path/to/my_raster.tif -F -t 10000x10000 my_raster | sudo -u postgres psql -d my_database
It's a 1 banded grayscale raster (lat/lon) with cell values representing some environmental factor on the ground. Hence, I simply want to get the cell value at a given lat/lon.
Following some examples I found I came up with the following SQL:-
SELECT ST_Value( rast, ST_SetSRID(ST_MakePoint(0,51.5),4326) ) AS rast_val FROM my_raster WHERE ST_Value( rast, ST_SetSRID(ST_MakePoint(0,51.5),4326) ) IS NOT NULL;
This seems to get the right value for me when I cross reference the same location loading the raster in QGIS.
My question is basically a sanity check if the above SQL is correct as I am not 100% sure of the WHERE clause.