Hi, Charlotte. 1. One "db file scattered read" wait would mean physical reads of several blocks, aka multi block I/O. 2. Direct path read would also be recorded as "physical reads". ================================ Dion Cho - Oracle Performance Storyteller http://dioncho.wordpress.com (english) http://ukja.tistory.com (korean) http://sites.google.com/site/otpack (tpack) ================================ On Wed, Nov 10, 2010 at 4:25 AM, Charlotte Hammond < charlottejanehammond@xxxxxxxxx> wrote: > Hi All, > > > For some of my sessions I see, for example: > > > V$SESS_IO shows 200,000 physical reads > > V$SESSION_EVENT shows < 100,000 total waits for “db file * read” (and > “read by > other session”) etc. > > Does that mean half my physical reads didn’t wait at all? How is that > possible? (I see this under high load - under low load number of reads is > approximately the same as the number of waits for the same SQL) > > > I'd be very grateful if you could explain this observation to me! (Platform > is > 10g on AIX) > > Thank you! > > Charlotte > > > > > -- > //www.freelists.org/webpage/oracle-l > > >