2013/3/27 Ken Tanzer <ken.tan...@gmail.com> > Basically you are getting Cartesian joins on the row output of >> unnest() > > > Well that's what I expected too. Except look at this example, after you > delete c: > > testdb=# DELETE FROM t2 where val='c'; > DELETE 1 > testdb=# SELECT * from t1, t2; > val | val > -----+----- > 1 | a > 1 | b > 2 | a > 2 | b > (4 rows) > > And compare to: > > SELECT unnest(array[1,2]),unnest(array['a','b']); > unnest | unnest > --------+-------- > 1 | a > 2 | b > (2 rows) > > You can see they are not the same! >
Ah yes, what I suggested is actually the equivalent to SELECT * FROM unnest(array[1,2]) u1,unnest(array['a','b']) u2; I seem to recall seeing the explanation for this before, although I'll be darned if I can remember what it is. FWIW this happens with other functions returning SETOF: testdb=# SELECT testdb-# generate_series(1,2) x, testdb-# generate_series(1,2) y; x | y ---+--- 1 | 1 2 | 2 (2 rows) testdb=# SELECT testdb-# generate_series(1,2) x, testdb-# generate_series(1,3) y; x | y ---+--- 1 | 1 2 | 2 1 | 3 2 | 1 1 | 2 2 | 3 (6 rows) Regards Ian Barwick
