Re: column aliases

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От Bruce Momjian
Тема Re: column aliases
Дата
Msg-id 200006080258.WAA09833@candle.pha.pa.us
обсуждение исходный текст
Ответ на Re: [HACKERS] column aliases  (Tom Lane <tgl@sss.pgh.pa.us>)
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OK, seems it is resolved.  We now throw a warning for the query.


> >> What it looks like to me is that we have a bug in the expansion of '*'.
> >> It should be generating columns for both the explicit and the implicit
> >> FROM clause, but it's evidently deciding that it should only produce
> >> output columns for the first one.
> 
> I thought that the behavior had something to do with the fact that
> the underlying table was the same for both the explicit and the implicit
> rangetable entry, but not so.  In fact, ExpandAllTables() deliberately
> refrains from expanding implicit entries, and always has AFAICT:
> 
>         /*
>          * we only expand those listed in the from clause. (This will
>          * also prevent us from using the wrong table in inserts: eg.
>          * tenk2 in "insert into tenk2 select * from tenk1;")
>          */
>         if (!rte->inFromCl)
>             continue;
> 
> I think the comment in parentheses is no longer applicable, but there
> are other sources of implicit rangetable entries besides this particular
> feature --- rules and set functions both seem to add them.  So I'm not
> sure what we might break by changing it.
> 
> I'm inclined to leave this behavior alone, and go back to the idea of
> emitting warning notices when an implicit FROM clause is added.
> 
>             regards, tom lane
> 


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