Re: [SQL] what is "cost"?

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От Bruce Momjian
Тема Re: [SQL] what is "cost"?
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Msg-id 199904232129.RAA14632@candle.pha.pa.us
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Ответ на Re: [SQL] what is "cost"?  (Gregory Holston <holston@itd.nrl.navy.mil>)
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> >     The cost value is only meaningful to the optimizer in comparing various
> >     query plans.
> > 
> I got the 72.98 on this table while doing a simple "select * from 
> publication" meanwhile I got nothing higher than 4 on any other table. Is this 
> indicative of a problem?

No.  It means the optimizer thinks it is going to have to do more work
to complete the query.  All other methods it used to complete the query
had a higher cost.  It is related to the number of rows in the table,
the indexes available, sorts needed, joins, etc.

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