RE: 'Theoretical' SQL question

[<Rick.Chevalier@xxxxxxxxxxxxxxx>]

I see what you're saying.  I misunderstood the statement and combined it with 
previous messages in my mind.  I agree.  The optimizer should at least stop 
when it gets to the matching RRN if not just go to the requested RRN.

Rick


-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx]On Behalf Of Kevin Wright
Sent: Thursday, January 20, 2005 4:56 PM
To: 'Midrange Systems Technical Discussion'
Subject: RE: 'Theoretical' SQL question


Hi Rick,

Similarly to Phil's presumption that a unique index (or primary key) on a
file would give the information that if you have found one like this there
won't be any others, I would assume that the use of equals and the RRN
function would be alike, and that the optimiser or engine would be able to
use the information to shortcut processing in 2 ways:

1. Retrieve the row "directly" via the rrn
2. Not look for any other rows

Regards,

Kevin Wright.


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