Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Mailing Lists -> Oracle-L -> Re: *Measuring sql performance (elapsed time and scalability) by number of logical reads

Re: *Measuring sql performance (elapsed time and scalability) by number of logical reads

From: Radoulov, Dimitre <cichomitiko_at_gmail.com>
Date: Tue, 2 May 2006 14:08:52 +0200
Message-ID: <029401c66de1$2e716390$1a03310a@MPILA9>


>I think you have been a bit short in the problem description.
>
> You just meant that all the requested data is already in buffer and no
> physical read is needed.
> Thanks but we have no information on the nature of the sql, the amount of
> data, the expected goal.
> Bad or good SQL is a ratio of these. What if I read one million blocks
> from my multi gig db block buffer
> to return a tiny rowset for the worse ever seen SQL, it will satisfy your
> prerequisite and still be very bad.

Excuse me for not being clear, I meant, theoretically speaking:

SQL 1 reads n1 blocks from buffer (no physical read) to complete, elapsed time t1
SQL 2 reads n2 (where n2 > n1) blocks from buffer (no physical read) to complete, elapsed time t2

t1 is greater than t2

Always theoretically/hypothetical speaking: could anyone comment the possibile reasons behind such behaviour.

Regards,
Dimitre

--
http://www.freelists.org/webpage/oracle-l
Received on Tue May 02 2006 - 07:08:52 CDT

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US