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buffer busy wait [message #536343]

Tue, 20 December 2011 05:55

dba_7722
Messages: 197
Registered: August 2010
Location: Delhi

Senior Member

Hello Expert,

I noticed oracle background process ora_fbda_padwsdpr is suffering from buffer busy wait. When i further finding the object, it was on SYS_FBA_FA tables.

Can you please suggest needed action and also what is this is causing BUFFER BUSY WAIT. Also to add we have disabled flashback database.

Thanks.

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Re: buffer busy wait [message #536346 is a reply to message #536343]

Tue, 20 December 2011 06:07

Michel Cadot
Messages: 68731
Registered: March 2007
Location: Saint-Maur, France, https...

Senior Member
Account Moderator

You can do nothing. These are Oracle owned tables.
Are you sure they are REALLY suffering?

Always post your Oracle version, with 4 decimals.

Regards
Michel

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Re: buffer busy wait [message #536347 is a reply to message #536343]

Tue, 20 December 2011 06:09

John Watson
Messages: 8964
Registered: January 2010
Location: Global Village

Senior Member

FBDA is the flashback data archive process, used for Total Recall. It is nothing to to do with Flashback Database, which is enabled by the RVWR recovery writer process.
Are you sure that the buffer busy wait is actually a problem? As FBDA is a background process, I wouldn't think it has any significant impact.

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Re: buffer busy wait [message #536350 is a reply to message #536347]

Tue, 20 December 2011 06:29

dba_7722
Messages: 197
Registered: August 2010
Location: Delhi

Senior Member

Thanks Michel & John.

While monitoring, it is found that few process suffered from BUFFER BUSY WAIT for long time. They are

       1 (oracle)                    526          1 buffer busy waits              Concurrency              0               1 WAITING
         1 (oracle)                    541          1 buffer busy waits              Concurrency              0               0 WAITING

When i looked for 526 process, it is fdba process.

Further finding the issue, we found it is on SYS_FBA_FA.


SQL> select
  2  o.object_name obj,
o.object_type otype,
  3    4  ash.SQL_ID,
  5  w.class
  6  from v$active_session_history ash,
  7  ( select rownum class#, class from v$waitstat ) w,
  8  all_objects o
  9  where event='buffer busy waits'
 10  and w.class#(+)=ash.p3
 11  and o.object_id (+)= ash.CURRENT_OBJ#
Order by sample_time;

SYS_FBA_FA                     TABLE
                                                   6014jdsc3d90v
                                                   6014jdsc3d90v
SYS_FBA_FA                     TABLE
                                                   6014jdsc3d90v
                                                   6014jdsc3d90v
SYS_FBA_FA                     TABLE
                                                   6014jdsc3d90v
                                                   6014jdsc3d90v

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Re: buffer busy wait [message #536351 is a reply to message #536350]

Tue, 20 December 2011 06:35

Michel Cadot
Messages: 68731
Registered: March 2007
Location: Saint-Maur, France, https...

Senior Member
Account Moderator

Quote:

it is found that few process suffered from BUFFER BUSY WAIT for long time

Nothing in your post shows it is waiting "for long time".

Regards
Michel

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