| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Zeugswetter Andreas SB <ZeugswetterA(at)wien(dot)spardat(dot)at> |
| Cc: | "'earthlink'" <NOSPAMnews(at)tinyvital(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: AW: Implicit order-by in Postgresql? |
| Date: | 2001-06-12 13:38:57 |
| Message-ID: | 8456.992353137@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Zeugswetter Andreas SB <ZeugswetterA(at)wien(dot)spardat(dot)at> writes:
>> If not, does an Order-by force a sort even if an index has the correct
>> order to satisfy the order-by?
> If a btree index is chosen that satisfies the order by, the sort is
> avoided.
And, of course, selection of that index is encouraged, because the
optimizer will realize that any other plan will require an explicit
sort step with extra costs.
Bottom line: say what you mean, don't try to outsmart the system.
If you want your results delivered in order, say ORDER BY.
regards, tom lane
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