I'm getting some odd results when running two generate_series calls in a
SELECT. When the two calls return the same number of rows you get that
many rows out:

# SELECT generate_series(1,3), generate_series(1,3);
generate_series | generate_series
-----------------+-----------------
1 | 1
2 | 2
3 | 3
(3 rows)

When the row counts differ you get the least common multiple number of
rows.

# SELECT generate_series(1,4), generate_series(1,2);
generate_series | generate_series
-----------------+-----------------
1 | 1
2 | 2
3 | 1
4 | 2
(4 rows)

I was personally expecting a cross join between them that would be
equivalent to

# SELECT * FROM generate_series(1,4) a, generate_series(1,2) b;
a | b
---+---
1 | 1
1 | 2
2 | 1
2 | 2
3 | 1
3 | 2
4 | 1
4 | 2
(8 rows)

Tested on 8.1.3 and CVS HEAD.

Kris Jurka

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Kris Jurka <books (AT) ejurka (DOT) com> writes:
Yup, this is the expected or at least historical behavior. It's not
entirely clear what you *should* get, which is one reason we ought to
deprecate SRFs in SELECT lists.

regards, tom lane

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