Re: select + insert vs. insert and catching exception

the routine is called very often and the insert is done very seldom (10000:1)

what gives you the certainty that the select is better? a load test?

"Jonathan Lewis" <jonathan_at_jlcomp.demon.co.uk> wrote in message news:amvn1b$k24$1$8300dec7_at_news.demon.co.uk...
>
> How often is it going to happen ?
> How often is it likely to fail on insert ?
>
> If the task runs rarely, who cares about a
> marginal overhead. If the task runs very
> frequently and the select usually succeeds
> then do the select first. If the task runs
> very frequently and the insert usually succeeds
> (at least 19 times out of 20) then consider
> doing the insert first.
>
> Inserting and getting a constraint breached
> is much more expensive than doing a single
> select which returns no rows.
>
> (Would you be doing an update if the select
> succeeds ? If so why not:
> update
> if no rows updated
> insert
>
> --
> Regards
>
> Jonathan Lewis
> http://www.jlcomp.demon.co.uk
>
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>
> Christoph Seidel wrote in message ...
> >what is better in respect of performance?
> >
> >select by primary key, if not found insert
> >
> >or
> >
> >insert and catch exception if primary key exists
> >
> >the table is quite small, less than 100 rows
> >
> >
>
>
Received on Thu Sep 26 2002 - 14:58:28 CDT