The help page for the PostGIS function ST_PixelAsCentroids has this line of code as a usage example:
SELECT x, y, val, ST_AsText(geom) FROM (SELECT (ST_PixelAsCentroids(rast, 1)).* FROM dummy_rast WHERE rid = 2) foo;

What is the word "foo" standing in for in this example?


1 Answer 1


'foo' is the name that has been assigned to the sub-selection. It has no function other than being syntactically necessary - a sub-selection in PostgreSQL must have a name assigned to it, but it does not matter what the name is. 'foo' was likely chosen because it is a common meaningless placeholder word used by programmers, similar to 'lorem ipsum' used by designers.


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