Finding the reasons for excessive logical IOs | Tanel Poder Consulting

[utterances-bot]

Finding the reasons for excessive logical IOs | Tanel Poder Consulting

There’s another interesting thread going on in Oracle-L, about understanding logical IOs and drilling down into their reasons. Of course sometimes (or rather usually) the excessive logical IOs come from a bad execution plan (when a nested loop loops over lots of datablocks again and again or a wrong index is used for driving a query etc), but sometimes the excessive LIOs are caused by some internal issues, like space management etc.
A convenient tool I use for reporting logical IO reasons is (again) my Snapper! It has an option “b” for reporting Buffer get reasons or as I use below – option “a” shows All information Snapper can show.
There are couple of gotchas though which make this approach imperfe

https://tanelpoder.com/2009/11/19/finding-the-reasons-for-excessive-logical-ios/

[DAV1963]

Hi,
I tried to run snapper on Active DataGuad host and got the message
declare * ERROR on line 1: ORA-16000: database or pluggable database is open for read-only access

Andre