RE: buffer busy waits PUZZLES

From: Cary Millsap <Cary.Millsap_at_hotsos.com>
Date: Tue, 17 May 2005 15:32:38 -0500
Message-ID: <2160.13631116358481.hotsos01.hotsos.com@MHS>

Ah! Credit to Gaja and Kirti for that one...

Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com
* Nullius in verba *

Visit www.hotsos.com for curriculum and schedule details...

-----Original Message-----
From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Alex Gorbachev
Sent: Tuesday, May 17, 2005 2:42 PM
To: sjaffarhussain_at_gmail.com
Cc: K Gopalakrishnan; oracle-l_at_freelists.org Subject: Re: buffer busy waits PUZZLES

As it was mentioned already, you probably don't have this problem. If you have around 50 tps, chances are that you perform much more logical IOs than few thousands "buffer busy waits".

You can have a look at v$system_event to see whether "buffer busy waits" is significant. Better yet to identify the sessions that have performance problem and check v$session_event or even better do 10046 trace. If you do not see buffer busy waits in top waits for the instance and do not have performance issues for specific sessions/transactions than you you've got CTD ("Compulsive Tuning Disorder") speaking Carry's language.

2005/5/10, The Human Fly <sjaffarhussain_at_gmail.com>:
> Gopal,

>=20

> Actually, I was digging at v$segment_statistic level. The following
> query has been used,

>=20

> select object_name,statistic_name,value from v$segment_statistics
> where statistic_name like '%buffer busy%'
> and value > 100
> order by value desc

>=20

> and the output is

>=20


> OBJECT_NAME                    STATISTIC_NAME                      VALUE

> ------------------------------ ------------------------------ ----------

> C_INTIMATION                   buffer busy waits                    8032

> CIS_AUDIT_TRAILH               buffer busy waits                    3739

> TRANSACTION_LOG                buffer busy waits                    2185

> FM_AUDIT_FORM                  buffer busy waits                    2032

> C_CUSTOMER                     buffer busy waits                    1768

> FM_OLTP_LOG                    buffer busy waits                    1476

> RB_RESTRAINTS                  buffer busy waits                     730

> RB_TRAN_HIST                   buffer busy waits                     653

> FM_ERROR_LOG                   buffer busy waits                     532

>=20

--=20
Best regards,
Alex Gorbachev
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Received on Tue May 17 2005 - 16:39:34 CDT