Re: Relate V$SQL.ROWS_PROCESSED/V$SYSSTAT.NAME='logical reads' ??

It's a very sensible idea.

There will be times where timing errors
make the numbers misleading, and there
will be statements where variations in the data distribution will make the average
logical I/Os per row misleading - that's just the typical problem with averages - but the measure of 'work done per row
acquired' is a useful clue to inefficient SQL. There are a few points to work through,
though, to refine the idea for (e.g.)
aggregate queries, multi-table queries,
queries with filtering sub-queries.

-- 
Regards

Jonathan Lewis

http://www.jlcomp.demon.co.uk/faq/ind_faq.html
The Co-operative Oracle Users' FAQ

http://www.jlcomp.demon.co.uk/seminar.html
Public Appearances - schedule updated April 5th 2005






"Spendius" <spendius_at_muchomail.com> wrote in message 
news:1117720046.433910.187010_at_f14g2000cwb.googlegroups.com...


> Hi,

> Do you think it would make sense to get:

> o at time t(1) the value of v$sql.rows_processed

>  and that of v$sysstat.value for name='logical reads'

> o then at time t(2) the same figures

> o etc.

> o then at time t(n) once again the same figures

>

> then substract from the first values, compute an average

> and be able to say "for this DB my overall rate of records

> returned per block read is <result of the avg>" ?

> Or is it complete rubbish ?

>

> Thanks.

>