Re: Optimizer, Cartesian Product & Extraneous Table

From: Joel Garry <joelga_at_pebble.ml.org>
Date: 6 May 1998 14:51:52 -0700
Message-ID: <6iqm1o$nqe$1@pebble.ml.org>

In article <01bd7885$aa632650$0100007f_at_gertrijs>, Gert Rijs <nospampleasegem_at_wirehub.nl> wrote:
>The extra table *is* being used: to create a cartesian product.
>How could the optimizer (or better, the parser) know that it isn't your
>intention?

From the fact that no other reference is being made to the table? Isn't this cartesian result just an artifact, since there is no relation?

>--
>reply address is altered to keep the spam down
>remove the nospamplease part to reply...
>Gert Rijs
>gem at wirehub.nl
>www.wirehub.nl/~gem
>
>
>Dr. J. Sylvan Katz <jskatz_at_coombs.anu.edu.au> wrote in article
><35501E15.4CCF162E_at_coombs.anu.edu.au>...
>> Can someone please explain why a cartesian product is produced if an
>> extraneous table name is accidently put in the from clause? Can't the
>> optimizer determine that the table is not being used?
>>
>> Regards
>> Sylvan
>>
>>

--
These opinions are my own and not necessarily those of Information Quest

jgarry@eiq.com                           http://www.informationquest.com

http://ourworld.compuserve.com/homepages/joel_garry "See your DBA?" I AM the @#%*& DBA! Received on Wed May 06 1998 - 16:51:52 CDT