Re: SQL-Optimizer Product!

In article <R3eoqDAGGCPzEwtb_at_jbdr.demon.co.uk>,   Jeremy Rickard <Jeremy_at_jbdr.demon.co.uk> wrote:
>
> In article <01bc3996$68258be0$061bf8ce_at_st-pierre95>, "Sam Q. Lang"
> <webmaster_at_sfi-software.com> writes
> >The new line of products captures SQL statements
> >sent to relational database engines, analyzes them and transforms them
> >into better performing alternatives that can automatically replace the
> >original SQL statements.
> The Oracle optimiser doesn't perform query rewrite itself then?
> --
> Jeremy Rickard

Yes, the optimizer does rewrite queries. However, there have been a lot of problems with Oracle cost-based optimizer - and it has not in fact re-written queries as well as it should have. However, I believe a lot of these problems were solved with 7.3. Prior to Oracle7 7.3, the performance of a query could vary greatly depending on the way the query is written.

Brenda

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