Re: Simple Join

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От Bruce Momjian
Тема Re: Simple Join
Дата
Msg-id 200512171456.jBHEunM07437@candle.pha.pa.us
обсуждение исходный текст
Ответ на Re: Simple Join  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-performance
Tom Lane wrote:
> Kevin Brown <blargity@gmail.com> writes:
> > I'm running 8.1 installed from source on a Debian Sarge server.  I have a
> > simple query that I believe I've placed the indexes correctly for, and I
> > still end up with a seq scan.  It makes sense, kinda, but it should be able
> > to use the index to gather the right values.
>
> I continue to marvel at how many people think that if it's not using an
> index it must ipso facto be a bad plan ...
>
> That plan looks perfectly fine to me.  You could try forcing some other
> choices by fooling with the planner enable switches (eg set
> enable_seqscan = off) but I doubt you'll find much improvement.  There
> are too many rows being pulled from ordered_products to make an index
> nestloop a good idea.

We do have an FAQ item:

     4.6) Why are my queries slow?  Why don't they use my indexes?

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