Subject Re[2]: [ib-support] Optimizer or De-optimizer ?
Author Carlos H. Cantu
Hi Ann !

Aquisi is the larger table. I tried to put the lookup field as part of the
Query but it didnt change the plan.

If I understand correctly, the PLAN can change when the tables grow up, so
the right PLAN today can be the wrong PLAN tomorrow, right ?

[]s

Carlos
WarmBoot Informatica - http://www.warmboot.com.br
Interbase-BR - http://www.interbase-br.com

AWH> At 11:44 AM 3/21/2001 -0300, Carlos H. Cantu wrote:

>>select a.*, f.forn_nome, f.forn_end
>>from AQUISI a
>>join forn f on f.cod_forn = a.cod_forn
>>
>>generated plan :
>>
>>PLAN JOIN (F NATURAL,A INDEX (RDB$FOREIGN57))
>>
>>f.cod_forn is the primary key of FORN. Why the optimizer isn't using the
>>index in this simple join ????

AWH> Which table is larger, aquisi or forn?

AWH> One or the other must be accessed naturally since the
AWH> look-up value comes from the tables and is not presented
AWH> as part of the query. If you have an aquisi, you can find
AWH> forns. If you have a forn, you can find an aquisi. If
AWH> you have neither, you must start somewhere.

AWH> Or is there another problem?


AWH> Regards,

AWH> Ann
AWH> www.ibphoenix.com
AWH> We have answers.



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