Re: Any thoughts?

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Fri, 30 Apr 2004 16:10:32 +0000 (UTC)
Message-ID: <c6ttpo$9ck$1@hercules.btinternet.com>

Session Logical I/Os is most likely to be the one that is correct.

If you want to mess yourself up completely, take a look at v$buffer_pool_statistics, which also records system level 'logical I/O'.

Looking at a 9.2 system that has been idling along for a while, I see:

v$buffer_pool

DB_BLOCK_GETS       2,502,196
CONSISTENT_GETS     1,099,488

v$sysstat

db block gets       1,402,528
consistent gets     2,131,216

There are several hundred routines which could be called to perform a 'logical I/O' - it's not too surprising that some of them update the wrong figure, or both, or neither, about what kind of logical I/O they have performed.

-- 
Regards

Jonathan Lewis
http://www.jlcomp.demon.co.uk

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"john" <orclwzrd_at_yahoo.com> wrote in message
news:4e062d34.0404290314.6eb7828c_at_posting.google.com...


> Anybody have any insight into the difference between the statistics

> 'session logical reads' and 'consistent gets' + 'db block gets' at

> both the session and system level. Usually the logical reads is

> determined by consistent gets + db block gets, session logical reads

> does not always equal this value. I'm just wondering why and if

> there's any reason to use one over the other. I've seen it both ways

> but not really any explanation. Seems that both should be correct.

>

> Of course, if I've missed the answer already posted sometime before,

> that would be nice to know too.

>

> Thanks for any feedback

>

> John

Received on Fri Apr 30 2004 - 11:10:32 CDT