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From "Naveen Murthy" <naveen.sriniv...@aricent.com>
Subject RE: Deadlock error
Date Fri, 18 Apr 2008 18:10:13 GMT
repeatable_read is one level higher than read-committed.

as name suggests, its meant to keep ur reads repeatable,
so typically, during a tran, at time T if u read a row,
then if u read again during the same tran at time T2, that row shud remain
constant. DB ensures this by locking that row (or page) after the first 
read.

in read-committed; after read in a tran, those rows/pages are released immediatly
so that other trans can modify them. but u lose the
repeatability as seen in other case.

look at ur usecase, for eg if most transactions involve only 
one actor accessing a set of resources ( for eg; if only one technician
is always allowed to work on a job) then chances of ur needing
repeatable read is very less, in that case better go with read
commited. lesser excl locks, even ur db will perf Lill faster.


Naveen


-----Original Message-----
From: Raj [mailto:nwiraj@yahoo.com]
Sent: Fri 4/18/2008 1:46 PM
To: Apache Torque Users List
Subject: Re: Deadlock error
 
More info.. the transaction isolation level in my.cnf
is set to REPEATABLE-READ.
My google research suggested setting this to
READ-COMMITED, need to review th implications before
changing this.
Also, not sure if this is the source of the problem.
Thanks,
Raj

my.cnf:

# Set the default transaction isolation level. Levels
available are:
# READ-UNCOMMITTED, READ-COMMITTED, REPEATABLE-READ,
SERIALIZABLE
transaction_isolation = REPEATABLE-READ

--- Raj <nwiraj@yahoo.com> wrote:

> All,
> 
> Getting a deadlock related error intermittently.
> The stack trace is as shown below.
> 
> Torque version: 3.2
> Mysql version: mysql  Ver 14.12 Distrib 5.0.33, for
> apple-darwin8.8.4 (i686) using  EditLine wrapper
> 
> Any hints?
> 
> Thanks,
> Raj
> 
> 
> org.apache.torque.TorqueException:
> java.sql.SQLException: Deadlock found when trying to
> get lock; Try restarting transaction message from
> server: "Lock wait timeout exceeded; try restarting
> transaction"
>         at
>
org.apache.torque.util.BasePeer.throwTorqueException(BasePeer.java:103)
>         at
>
org.apache.torque.util.BasePeer.insertOrUpdateRecord(BasePeer.java:639)
>         at
>
org.apache.torque.util.BasePeer.access$000(BasePeer.java:73)
>         at
>
org.apache.torque.util.BasePeer$IOUProcessCallback.process(BasePeer.java:1254)
>         at
>
org.apache.torque.util.BasePeer.processTables(BasePeer.java:1645)
>         at
>
org.apache.torque.util.BasePeer.doUpdate(BasePeer.java:1234)
> 
> 
> 
>      
>
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