> (BTW, ordinary SELECT DISTINCT has this same sort of problem if you try
> to ORDER BY an expression that doesn't appear in the target list.
> SQL92 avoids the issue by not allowing you to ORDER BY expressions that
> aren't in the target list, period. We do allow that --- but not when
> you use DISTINCT. Essentially, I want to enforce that same restriction
> for DISTINCT ON.)
> The other piece of the puzzle would be to document that DISTINCT ON
> keeps the first tuple out of each set with the same DISTINCT ON value.
> Does that sound like a plan?
Yes, very clear. Good.
Bruce Momjian | http://www.op.net/~candle
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
+ If your life is a hard drive, | 830 Blythe Avenue
+ Christ can be your backup. | Drexel Hill, Pennsylvania 19026
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