Re: [HACKERS] union and LIMIT problem
От | Bruce Momjian |
---|---|
Тема | Re: [HACKERS] union and LIMIT problem |
Дата | |
Msg-id | 199910071739.NAA02643@candle.pha.pa.us обсуждение исходный текст |
Ответ на | Re: [HACKERS] union and LIMIT problem (Tom Lane <tgl@sss.pgh.pa.us>) |
Список | pgsql-hackers |
> >>>> * UNION with LIMIT fails > >> > >> and must fail by it's implementation. LIMIT is handled by the > >> outermost executor loop, suppressing OFFSET result tuples and > >> stopping execution after LIMIT results sent to the client. > > > Ah, but it works sometimes: > > Well, the real question is what do you mean by "works" or "fails". > In particular, do you think that LIMIT applies to the overall result > of the whole query, or to any one sub-select? Should apply to overall result, like ORDER BY. > > IIRC, ORDER BY is supposed to apply to the end result (and you can > only write it at the very end of the query, not after a sub-select), > and I'd vote for making LIMIT work the same. In which case the > executor should be fine, and we probably just have a problem with > the parser hanging the info on the wrong node of the querytree... > > regards, tom lane > -- Bruce Momjian | http://www.op.net/~candle maillist@candle.pha.pa.us | (610) 853-3000+ If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania19026
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