Thanks Kirti and Paul for the reply.
The instance is up for only 3 days. We know there are
very heavy inserts in the database.
Yes, There are high waits for 'buffer busy waits'
event in V$SYSTEM_EVENT view. But I didn't see 'buffer
busy waits' in V$SESSION_EVENT. I may try to increase
the freelist to 12(I don't know whether it helps,
anyway we have 12 Java threads insert data into the
same table concurrently).
Thanks,
Chris
- "Deshpande, Kirti" <kirti.deshpande_at_verizon.com>
wrote:
> How long has the instance been up?
>
> It appears that the application is trying to read
> the same data blocks &/or
> more sessions are trying to update the same data
> block or the free lists may
> need to be set properly to support concurrent
> INSERTs.
>
> So, before changing anything for DBWR process, I
> would suggest to check the
> top wait events from V$SYSTEM_EVENT view. You may
> see high waits for 'buffer
> busy wait' event. If so, I would trace it further
> using V$SESSION_EVENT and
> V$SESSION_WAIT (P1, P2 values) to find out the 'hot'
> segment and the file.
> You may have to review the pctfree, freelists,
> extent sizes etc. to address
> 'buffer busy waits'.
>
> For all you know, it could be just an application
> issue in scheduling the
> processes properly.
>
> And to answer your question about setting
> DBWR_WRITE_PROCESSES(actually the
> parameter is DB_WRITER_PROCESSES) you may want to
> check out Note# 97291.1 on
> Metalink. It has some good information.
>
> HTH,
>
> - Kirti
>
>
> -----Original Message-----
> Sent: Tuesday, January 15, 2002 7:16 PM
> To: Multiple recipients of list ORACLE-L
>
>
> Hi, gurus:
> The database is oracle8.1.7.2.1 on win2k machine
> with 1 CPU and two hard drives. When I query
> v$waitstat, I got the following:
>
> CLASS COUNT TIME
> ------------------ ---------- ----------
> data block 246901435 132690159
> segment header 4869 8018
> undo block 20986 38476
> undo header 1895 1556
>
> seems like I need to set DBWR_WRITE_PROCESSES to a
> higher number, what number should I choose, 2 or
> bigger?
>
> Also, what other problems can you see from the last
> query, other than we need to add some more RBS?
>
> Thanks,
>
> Chris Harvest.
>
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Received on Wed Jan 16 2002 - 13:05:21 CST
