The other aspect of the standard that the Postgres implementation does not
currently support is the fact that unnest is supposed to be defined in terms of
laterally derived subqueries, e.g. you should be able to unnest another element
from a from list entry laterally on the left.
CREATE TABLE t
Note the standard also supports unnesting multiple arrays concurrently, the
rule for handling arrays with different lengths is to use null padding of the
shorter array.
SELECT * FROM
UNNEST( ARRAY[5,2,3,4],
ARRAY['hello', 'world'] )
WITH ORDINALITY AS t(a,b,i);
a b i
--
