Some reasons for the difference: a) A single disk read could get more than 1 block b) queries may already find blocks in the cache and thus not need a disk read c) a query may revisit the same block over and over without ever going back to disk
The reason we look at both is 'disk_reads' tell us what is possibly causing stress on the IO subsystem, 'buffer gets' tells us what is causing stress on cpu. hth connor --- Erik Williams <[EMAIL PROTECTED]> wrote: > > I am trying to identify the most harmful statements > in an application. From > the Oracle Performance and Tuning Tips and > Techniques book, I found two > statements. Both are looking at the statements > contained in the v$sqlarea. > The first looks at statements with a high number of > buffer gets and the > other looks at the statements with a high number of > disk reads. Some of the > statements appear in both lists, but some in only > one. If all of the disk > reads are moving blocks into the buffer cache, what > is the difference > between the two measures? Can anyone explain the > difference between the two > measures? > > Thanks. > Erik > > -- > Please see the official ORACLE-L FAQ: > http://www.orafaq.com > -- > Author: Erik Williams > INET: [EMAIL PROTECTED] > > Fat City Network Services -- (858) 538-5051 FAX: > (858) 538-5051 > San Diego, California -- Public Internet > access / Mailing Lists > -------------------------------------------------------------------- > To REMOVE yourself from this mailing list, send an > E-Mail message > to: [EMAIL PROTECTED] (note EXACT spelling of > 'ListGuru') and in > the message BODY, include a line containing: UNSUB > ORACLE-L > (or the name of mailing list you want to be removed > from). You may > also send the HELP command for other information > (like subscribing). ===== Connor McDonald http://www.oracledba.co.uk (mirrored at http://www.oradba.freeserve.co.uk) "Some days you're the pigeon, some days you're the statue" ____________________________________________________________ Nokia Game is on again. Go to http://uk.yahoo.com/nokiagame/ and join the new all media adventure before November 3rd. -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: =?iso-8859-1?q?Connor=20McDonald?= INET: [EMAIL PROTECTED] Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
