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Home -> Community -> Usenet -> c.d.o.server -> Re: latch: cache buffers chains
wagen123_at_yahoo.com wrote:
> Oracle 10g 10.2.0.2 (64 bit)
> 2 -node RAC
>
> I am seeing only ONE session waiting on a CBC latch. Followed the
> metalink docs to identify the hot block without luck. See below.
>
> select count(*), event from gv$session_wait where event like '%latch%'
> group by event order by 1 desc;
>
> COUNT(*) EVENT
> ---------- -----------------------------------
> 1 latch free
>
>
> SELECT count(*) NUM_WAITERS, p1 FILE#, p2 BLK#, p3 CLASS FROM gv
> $session_wait WHERE event = 'latch: cache buffers chains' GROUP BY p1,
> p2, p3;
>
> NUM_WAITERS FILE# BLK# CLASS
> ----------- ---------- ---------- ----------
> 1 2629049624 122 0
>
> SELECT owner,segment_name,segment_type FROM dba_extents WHERE
> file_id=2629086424 and 122 BETWEEN block_id AND block_id + blocks;
>
> no rows selected.
>
> Any ideas to determine the root cause.
> What does CLASS=0 mean?
> File=2629049624 does not exit.
>
> Any help/pointers would be appreciated.
>
> Thanks
> wagen
>
Are you sure you have the proper descriptions for the 3 parameters? I get the following:
SQL> select name,parameter1,parameter2,parameter3
2 from v$event_name where name like 'latch:%';
NAME
So P1 is not FILE# as suggested, but the address. P3 is the number of tries for the latch.
Is this the only wait event your session is hung up on? Also experiencing 'buffer busy waits' by chance?
Cheers,
Brian
-- =================================================================== Brian Peasland dba_at_nospam.peasland.net http://www.peasland.net Remove the "nospam." from the email address to email me. "I can give it to you cheap, quick, and good. Now pick two out of the three" - Unknown -- Posted via a free Usenet account from http://www.teranews.comReceived on Tue Apr 24 2007 - 09:55:43 CDT
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