Tom Lane <[EMAIL PROTECTED]> writes: > This was discussed before --- see the archives. I believe the > conclusion was that the results would actually be nondeterministic > if we used two sort steps (that's what the code comment means by > "rather unpredictable").
Does the non-determinism you're referring to result from an ORDER BY on a non-deterministic expression, or the non-determinism that results from picking an effectively random row because the ORDER BY isn't sufficient? I searched the archives and found Stephen Szabo's comment[1] that: The query you've written is potential non-deterministic if you have a people_id that has multiple rows with different last names that meet the where clause. Which seems like an unconvincing justification for rejecting the query: we accept DISTINCT ON with no ORDER BY clause at all, for example. -Neil [1] http://archives.postgresql.org/pgsql-hackers/2001-07/msg00588.php ---------------------------(end of broadcast)--------------------------- TIP 9: the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
