| From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | "alexandre paes :: aldeia digital" <alepaes(at)aldeiadigital(dot)com(dot)br>, pgsql-sql(at)postgresql(dot)org |
| Subject: | Re: LIMIT Optimization |
| Date: | 2002-01-25 17:54:57 |
| Message-ID: | 200201251754.g0PHsvG01436@candle.pha.pa.us |
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| Lists: | pgsql-sql |
Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > So it forces our LIMIT optimization, without limiting the number of rows
> > returned. That seems to be of questionable value. The only value I can
> > see for it is for CURSOR queries but I don't think we can start
> > returning rows from even a cursor until the entire query is done
> > executing.
>
> Not so at all. However, CURSORs are already optimized on the assumption
> that not all the rows will actually get fetched.
So, it is only valuable for cursors or can we return results before the
entire query finishes for non-cursors. The "No so at all" part has me
confused.
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
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