AW: read by other session events
- From: Petr Novak <Petr.Novak@xxxxxxxxxxxx>
- To: Grzegorz Goryszewski <grzegorzof@xxxxxxxxxx>, "lyallbarbour@xxxxxxxxxxxxxxx" <lyallbarbour@xxxxxxxxxxxxxxx>
- Date: Thu, 11 Nov 2010 07:34:24 +0000
Hi,
Probably there was inefficient SQL statement.
You can find in ASH which statement was mostly connected to this wait. In AWR
you can verify if this statement changed the execution plan. Bouncing the DB
probably reverted the statement to old good plan.
Usually , you cannot tune the waits, but if you tune the statements, the waits
will be reduced ;-)
Best Regards,
Petr
Von: Grzegorz Goryszewski [grzegorzof@xxxxxxxxxx]
Gesendet: Mittwoch, 10. November 2010 23:26
Bis: lyallbarbour@xxxxxxxxxxxxxxx
Cc: oracle-l@xxxxxxxxxxxxx
Betreff: Re: read by other session events
>
>
> This morning we had our production 10.2.0.4 database come to practically a
> grinding halt with lots of I/O requests in Grid. running ADDM and ASH
> reports, there were, at first, problems with Segments that needed to be
> tuned. Then the next ADDM reports talked about "read by other session"
> events being 100% the major problem.
> After looking through Oracle Support and more and more help desk calls coming
> in, we decided to bounce the database. This, of course, solved our problem.
>
> I don't really understand what "read by other session" events are, so if
> someone can clarify that, that would be helpful. From what i read, they are
> memory waits for the data blocks in the buffer cache. Different logins
> requesting the same blocks in memory... i think. Even if that's right, i
> guess i still don't really understand what that means
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Hi,
try with this page:
http://sites.google.com/site/embtdbo/wait-event-documentation/oracle-io-waits#TOC-read-by-other-session
Regards.
Greg
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