[MonetDB-users] Unexpected results with COALESCE and aggregates

MonetDB SR5 behaves unexpectedly when we've tried to use COALESCE with aggregates, here's an example:

sql>CREATE TABLE tmp(a int); sql>SELECT SUM(a) FROM tmp; +-------+ | sum_a | +=======+ | 0 | +-------+ sql>SELECT MIN(a) FROM tmp; +-------------+ | min_a | +=============+ | null | +-------------+ sql>SELECT COALESCE(MIN(a), 0) FROM tmp; sql>

For the first SELECT I would expect NULL, the second SELECT is okay, but I expect a result for the third!

Here's what PosgreSQL does:

bob=# CREATE TABLE tmp(a int); CREATE TABLE bob=# SELECT SUM(A) FROM tmp; sum -----

(1 row)

bob=# SELECT MIN(a) FROM tmp; min -----

(1 row)

bob=# SELECT COALESCE(MIN(a), 0) FROM tmp; coalesce ---------- 0

-bob