RE: Deadlock inserting into same rowid (different block)

From: Patterson, Joel <jpatterson_at_entint.com>
Date: Wed, 20 Mar 2013 11:25:50 -0400
Message-ID: <C1117B1AA0340645894671E09A7891F714F8833843_at_EIHQEXVM2.ei.local>

I probably shouldn't ask, but how does one session know that another session has uncommitted values about to be committed that would conflict with what itself?

But aside from that, I wish to report back to the developers that are asking about this that --... essentially it is an application issue... and provide some suggestions such as the order of tables and/or rows... but more specifically in this case, from what I am reading, it is counter productive to report back that the trace file is incorrect... Does it imply that this could be an anomaly and just wait and see if it is a reoccurring issue? This is probably new code; the errors are in a UAT DB.

Joel Patterson
Database Administrator
904 928-2790

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Joel Patterson
Sr. Database Administrator | Enterprise Integration
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From: Jonathan Lewis [mailto:jonathan_at_jlcomp.demon.co.uk]
Sent: Wednesday, March 20, 2013 11:09 AM
To: Patterson, Joel
Cc: oracle-l_at_freelists.org
Subject: Re: Deadlock inserting into same rowid (different block)


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

----- Original Message -----
From: "Patterson, Joel" <jpatterson_at_entint.com>



|

| 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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Received on Wed Mar 20 2013 - 16:25:50 CET