AW: AW: AW: AW: [HACKERS] Some notes on optimizer cost estimates

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От Zeugswetter Andreas SB
Тема AW: AW: AW: AW: [HACKERS] Some notes on optimizer cost estimates
Дата
Msg-id 219F68D65015D011A8E000006F8590C603FDC228@sdexcsrv1.f000.d0188.sd.spardat.at
обсуждение исходный текст
Список 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_mandantAND 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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