Oracle-L: Re: Buffer busy waits are 10.96% of non-idle waits

From: Kavitha Muthukumaren <Kavitha.Muthukumaren_at_oracle.com>
Date: Thu, 11 Jul 2002 13:28:37 -0800
Message-ID: <F001.00495B92.20020711132837@fatcity.com>

Hi ,

TOAD gives this alarm often. what does it mean ? which view will give me the wait statistics ?

Answer :

Please run STATSPACK to if this is one of the top waitevents to check if the percentage of wait - can be treated as problematic one

SELECT p1 "File", p2 "Block", p3 "Reason"

FROM v$session_wait
WHERE event='buffer busy waits'
Repeatedly run the above statement and collect the output. After a period of time sort the results to see which file & blocks are showing contention:

" it occurs when a session cannot access a block because it is in use by another session. The two most common causes are insufficient free lists for a table or insufficient rollback segments. " --- IS THIS THE REASON ?

Answer:

Yes on top of the wait event could also occur could also occur if

if the application is going against a set of same blocks (hot blocks)

Thanks,
Kavi

oraora oraora wrote:

> Guys,
>
> " Buffer busy waits are 10.96% of non-idle waits "
>
> TOAD gives this alarm often. what does it mean ? which view will
> give me the wait statistics ?
>
> " it occurs when a session cannot access a block because it is in
> use by another session. The two most common causes are
> insufficient free lists for a table or insufficient rollback
> segments. " --- IS THIS THE REASON ?
>
> what should be the value of this , i mean , the safe limits ?
>
> How do i approach and solve this issue ?
> kindly enlighten me.
>
> TIA.
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Kavitha Muthukumaren
  INET: Kavitha.Muthukumaren_at_oracle.com

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Received on Thu Jul 11 2002 - 16:28:37 CDT