Hi All,
It is taking twice as long to do a single query for multiple lat/lon
pairs ( 10,000 of them ) than to iterate over the pairs and query for
each. I would have thought that the single query would be faster.
The queries are as follows:
Called once:
select ST_Value(rast, ST_Transform(ST_SetSRID(ST_Point(s.lon, s.lat),
4326), ST_SRID(rast))) from srtm3 cross join( VALUES (lat1,lon1),
(lat2,lon2), (lat3,lon3), ... (lat10000, lon10000) ) as s(lat,lon) where
filename='N38E126.hgt';
Called for each lat/lon pair:
select ST_Value(rast, ST_Transform(ST_SetSRID(ST_Point(lon, lat), 4326),
ST_SRID(rast))) from srtm3 where filename='N38E126.hgt';
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