Re: getting the ranks out of items with SHARED
| От | Tom Lane | 
|---|---|
| Тема | Re: getting the ranks out of items with SHARED | 
| Дата | |
| Msg-id | 26967.1121205783@sss.pgh.pa.us обсуждение исходный текст | 
| Ответ на | getting the ranks out of items with SHARED (Janning Vygen <vygen@gmx.de>) | 
| Ответы | postgresql SSL off Re: getting the ranks out of items with SHARED | 
| Список | pgsql-general | 
Janning Vygen <vygen@gmx.de> writes:
> I have a guess, what happens here: The order of the subselect statement is
> dropped by the optimizer because the optimizer doesn't see the "side-effect"
> of the ranking function.
That guess is wrong.
I think the problem is that you are trying to update multiple rows in
the same statement, which would require a "reset ranking" between each
row, which this approach doesn't provide for.
The whole thing looks mighty fragile in other ways; anything involving a
single global variable isn't going to work nicely in very many cases.
Consider casting your solution as an aggregate instead...
            regards, tom lane
		
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