Re: SQL Hints

From: Michel Cadot <micadot{at}altern{dot}org>
Date: Wed, 24 Mar 2004 22:09:32 +0100
Message-ID: <4061f959$0$8924$636a15ce@news.free.fr>

"Marek Babski" <user72_at_go2.pl> a écrit dans le message de news:11d263ba.0403241212.7ec79596_at_posting.google.com...
> > Have a look at:
> > http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96533/hintsref.htm#8326
>
> Your link is realy use useful but I still don't understand how works
> methods which optimizer choose for execution - for example:
> SELECT accounts.balance, customers.last_name, customers.first_name
> FROM accounts, customers
> WHERE accounts.customer_id = customers.customer_id;
>
> the optimizer chooses either (1) a nested loops operation, (2) a
> sort-merge operation, or (3) a hash operation to join these tables
>
> How in short description works (1),(2),(3). Particulary I have no
> idea about differences between (1) and (3) ??? (but also (2) is not
> clear for me)

OK for the different join methods, have a look at: http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96533/optimops.htm#39473

Regards
Michel Cadot Received on Wed Mar 24 2004 - 15:09:32 CST