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Re: Single stack optimistic lock exception?
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Re: Single stack optimistic lock exception?


  • Subject: Re: Single stack optimistic lock exception?
  • From: Ken Anderson <email@hidden>
  • Date: Fri, 24 Sep 2010 13:50:54 -0400

It's a good question, and one I can probably check for when the exception happens.  Will that be in the optimistic lock exception?  Or do I have to hunt for it?

On Sep 24, 2010, at 12:53 PM, Mike Schrag wrote:

> just to make sure -- does the database have the new value and the snapshot has the old, or vice versa?
>
> ms
>
> On Sep 24, 2010, at 12:50 PM, Ken Anderson wrote:
>
>> It's Oracle RAC, so yes, a cluster.
>>
>> Yes, I'm REALLY sure it's single threaded.
>>
>> Yes, no way for someone else to change those rows, since we audit the tables with a trigger, and they weren't modified by anything else.
>>
>> The data type of the trans_id column is Number (12,0)
>>
>> Ken
>>
>> On Sep 24, 2010, at 12:37 PM, Miguel Arroz wrote:
>>
>>> Hi!
>>>
>>> What kind of DB are you using? Is it a single server, or a cluster?
>>>
>>> Are you REALLY sure it's single threaded (although that should not make a difference, because OL doesn't work anyway ;) )?
>>>
>>> Are you REALLY sure no other app, person, alien, cosmic ray, etc, is changing the conflicting rows at the same time?
>>>
>>> (Not my suggestion, but really good point ;) ) What is the data type of the column you use for locking?
>>>
>>> Regards,
>>>
>>> Miguel Arroz
>>>
>>> On 2010/09/24, at 16:56, Ken Anderson wrote:
>>>
>>>> All,
>>>>
>>>> I have an odd problem I'm wondering if anyone else has seen before.
>>>>
>>>> I have apps that do high throughput processing of data - many times a second.  It is single threaded, and uses a single EOF stack.  I'm sure it's single threaded because the requests are coming in via an inbound queue, not any kind of front end.
>>>>
>>>> Every once in a while under significantly high load, I get a few optimistic lock exceptions in a row, on rows that are only being touched by this app.  We audit every update, and I can look into the audit tables and verify that nothing else has modified the record except this app.
>>>>
>>>> It's almost like the snapshot has not been recorded properly before the next request is processed, so EOF thinks something else updated the value.
>>>>
>>>> Our locking is implemented on a single column, trans_id, which is updated with every save.  The audit table also saves the trans_id that's responsible for moving the record into audit, and all the values match in succession.
>>>>
>>>> Has anyone had anything like this happen?  Running 5.4.3 on Linux.  and no... no Wonder.
>>>>
>>>> Ken _______________________________________________
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>>>
>>
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  • Follow-Ups:
    • Re: Single stack optimistic lock exception?
      • From: Mike Schrag <email@hidden>
References: 
 >Single stack optimistic lock exception? (From: Ken Anderson <email@hidden>)
 >Re: Single stack optimistic lock exception? (From: Miguel Arroz <email@hidden>)
 >Re: Single stack optimistic lock exception? (From: Ken Anderson <email@hidden>)
 >Re: Single stack optimistic lock exception? (From: Mike Schrag <email@hidden>)

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