RE: Deadlock inserting into same rowid (different block)

From: "Patterson, Joel" <jpatterson@xxxxxxxxxx>
To: "jonathan@xxxxxxxxxxxxxxxxxx" <jonathan@xxxxxxxxxxxxxxxxxx>
Date: Wed, 17 Apr 2013 08:49:37 -0400
Update:  I have been Following up with oracle support on this - but...   I sent 
the analyst Jonathan Lewis's url posted on Apr 13th 
http://jonathanlewis.wordpress.com/2013/04/13/deadlocks/ -- but believe it or 
not, based on his response so far, I do not believe he read it.  So I 
essentially sent the following.

The blocks in the deadlock graph below refer to a FK index, 
SCHEDULEDL_CONTRACT_FK, and a COSAUDIT table. The Index for 
SCHEDULEDL_CONTRACT_FK is on table SCHEDULEDLINEITME, and the foreign key is 
between the SCHEDULEDLINEITEM table and the CONTRACT table.

COSAUDIT in the deadlock graph isn't even involved anywhere; in the foreign key 
index, or the related tables in the FK constraint -- yet there it is in the 
deadlock graph, block 276654.  Hence I am starting to understand - nothing like 
a picture.

The next step would be to try and dump the blocks - but one is an index block, 
and the other is not related to the two insert statements attempting to insert 
into SCHEDULEDLINEITEM.

So:  Is would a dump of the FK block be of value?     Is such a dump in any 
event also be left over garbage just like the COSAUDIT block making it 
untrustworthy even if there was useful information there, (I can't think of 
when it would be useful, I'm just asking for theoretical reasons)?


DBMON @ cosacc> select tablespace_name, segment_type, owner,
2 segment_name
3 from dba_extents where file_id = 6 and 433952 between block_id AND block_id + 
blocks-1;
TABLESPACE_NAME                SEGMENT_TYPE       OWNER                         
 SEGMENT_NAME
------------------------------ ------------------ 
------------------------------ --------------------------
DATA1                          TABLE              COS                           
 COSAUDIT

DBMON @ cosacc> select tablespace_name, segment_type, owner,
2 segment_name
3 from dba_extents
4 where file_id = &file_num
5 and &block_num between block_id AND block_id + blocks-1;
Enter value for file_num: 6
Enter value for block_num: 276654

TABLESPACE_NAME                SEGMENT_TYPE       OWNER                         
 SEGMENT_NAME
------------------------------ ------------------ 
------------------------------ --------------------------
DATA1                          INDEX              COS                           
 SCHEDULEDL_CONTRACT_FK



Joel Patterson
Database Administrator
904 928-2790

From: Patterson, Joel
Sent: Thursday, April 11, 2013 12:01 PM
To: 'jonathan@xxxxxxxxxxxxxxxxxx'
Cc: 'oracle-l@xxxxxxxxxxxxx'
Subject: RE: Deadlock inserting into same rowid (different block)

Hello Jonathan,
I had created an SR on this issue, which is about to run its course.
In midst of it I asked if the slot #'s being zero is expected behavior in this 
situation.   The response was why would it not be expected -- we start the 
number with 0,1,2 ... etc.  It is the slot on the ITL it is waiting for.
Is there some elaboration which would help me discuss it further?
I plan to close out the SR as it has basically run its course at this point and 
the problem was identified and fixed - and I believe the forum was updated as 
well.   Essentially two batch jobs running at the same time, however I wanted 
to explore this before I close taking advantage of the fact that the SR is open 
already.

Best Regards,

2013/3/20 Jonathan Lewis 
<jonathan@xxxxxxxxxxxxxxxxxx<mailto:jonathan@xxxxxxxxxxxxxxxxxx>>

The deadlock pattern is indicative of collisions on a unique constraint.
They're both trying to insert primary / unique key values already inserted
but not yet committed by the other session.

Given that the slot numbers are both zero, it's likely that they're being
reported incorrectly - Oracle doesn't clean out the wait information for
every single wait, so these could be the file and block (with zero row) for
early buffer busy waits, or read by other session or some such.

Regards

Jonathan Lewis
http://jonathanlewis.wordpress.com/all-postings

Author: Oracle Core (Apress 2011)
http://www.apress.com/9781430239543


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From: "Patterson, Joel" <jpatterson@xxxxxxxxxx<mailto:jpatterson@xxxxxxxxxx>>

|
| Deadlock graph:
|                       ---------Blocker(s)--------  ---------Waiter(s)---------
| Resource Name          process session holds waits  process session holds
waits
| TX-001a0015-00014787        34      90     X             32       3
S
| TX-00190008-0000601b        32       3     X             34      90
S
|
| session 90: DID 0001-0022-00000327      session 3: DID 0001-0020-000009E9
| session 3: DID 0001-0020-000009E9       session 90: DID
0001-0022-00000327
|
| Rows waited on:
|  Session 90: obj - rowid = 00030CE5 - AAAwzlAAGAABDiuAAA
|  (dictionary objn - 199909, file - 6, block - 276654, slot - 0)
|  Session 3: obj - rowid = 00030CE5 - AAAwzlAAGAABp8gAAA
|  (dictionary objn - 199909, file - 6, block - 433952, slot - 0)
|
|
|

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RE: Deadlock inserting into same rowid (different block)

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