From: | Zeugswetter Andreas SB <ZeugswetterA(at)wien(dot)spardat(dot)at> |
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To: | "'hackers(at)postgresql(dot)org'" <hackers(at)postgreSQL(dot)org> |
Subject: | AW: AW: AW: AW: [HACKERS] Some notes on optimizer cost estimates |
Date: | 2000-01-27 09:55:10 |
Message-ID: | 219F68D65015D011A8E000006F8590C603FDC228@sdexcsrv1.f000.d0188.sd.spardat.at |
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Lists: | pgsql-hackers |
> >Yes, I think syntax to force or disallow a particular index,
> >choose a join method or order, force/disallow seq scans ...
> >is sometimes useful.
> >Even Informix, who always refused to supply such a feature
> >now has it.
>
> Can you give some sample syntax, for those of us who aren't
> really database people but merely trying to maintain a facade? :)
SELECT {+ INDEX (a auftragsbeleg_index2)} a.id_beleg
FROM auftragsbeleg a, instparameter i WHERE
a.num_mandant=i.num_mandant AND cod_prioritaets=?
AND num_prior_eingang<?
SELECT {+ ORDERED } * from tab1, tab2, tab3 .....
SELECT {+ FULL (tab1) } * from tab1, tab2, ....
SELECT {+ AVOID_FULL (tab1) } * from tab1, tab2, ....
Informix places the directives in comments, so that the resulting sql
does not violate SQL92.
The directive is identified by the {+
Andreas
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