At 07:29 AM 7/16/2008, Tom Lane wrote:
Steve Midgley <[EMAIL PROTECTED]> writes:
Interesting. You realize of course that sorting by the same
expression
twice is completely redundant? I haven't dug through the code yet but
Thanks Tom. Yeah, I was a little embarrassed to throw this code up on
the list b/c it's pretty weak. It's basically machine written - so
sometimes the CASE features a different "THEN X ELSE Y" order.
I think what is happening is that ORDER BY knows that and gets rid of
the duplicate entries while DISTINCT ON fails to do so. Or some story
approximately like that. It should be fixed, but the immediate
workaround is just to get rid of the redundant sort keys:
I don't know if this will help track down the problem, but I figured
out last night that ORDER BY is totally fine with having TWO duplicate
entries, so long as I only put ONE entry in the DISTINCT ON area.
Of course removing the duplicate from both areas is the correct
solution and I broke down and hacked that into the auto-sql-writing
code and so my immediate problem is solved. I'm happy to file this as a
ticket for Pg (please point me to your ticket tool as I've never used
it). This is not a very big deal but Pg has such a high compliance with
wacky-but-valid SQL it does seem like it should be fixed just because.
Let me know if I can help on that.
Best,
Steve
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