RE: Deadlock inserting into same rowid (different block)

From: Patterson, Joel <jpatterson_at_entint.com>
Date: Wed, 20 Mar 2013 11:27:48 -0400
Message-ID: <C1117B1AA0340645894671E09A7891F714F8833845_at_EIHQEXVM2.ei.local>

Thanks Mohamed, I believe Jonathan only kept the relevant portions of my original where I mentioned that the FK is indexed. "Object rowed 199909 is a FK on child table. The foreign_key is indexed (one column to one column PK in parent)..."

Joel Patterson
Database Administrator
904 928-2790

From: mohamed houri [mailto:mohamed.houri_at_gmail.com] Sent: Wednesday, March 20, 2013 11:21 AM To: jonathan_at_jlcomp.demon.co.uk
Cc: Patterson, Joel; oracle-l_at_freelists.org Subject: Re: Deadlock inserting into same rowid (different block)

In addition to what Jonathan has already clarified, I want to add that for a deadlock to be eventually due to a missing index on FK the deadlock graph should at least show one TM enqueue(DML enqueue). In your case both enqueues are of Transaction(TX) enqueue type. So your deadlock has a big chance to not being related to an unindexed FK

Best regards
Mohamed Houri
www.hourim.wordpress.com<http://www.hourim.wordpress.com>

2013/3/20 Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk<mailto:jonathan_at_jlcomp.demon.co.uk>>

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_at_entint.com<mailto: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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Bien Respectueusement
Mohamed Houri

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Received on Wed Mar 20 2013 - 16:27:48 CET