Re: bzr commit into mysql-5.0-bugteam branch (alfranio.correia:2705) Bug#40337

[alfranio correia]

He Zhenxing wrote:
> Lars Thalmann wrote:
>   
>> On Mon, Nov 03, 2008 at 03:34:30PM +0800, He Zhenxing wrote:
>>     
>>> 3) Try to reduce the relay logs need to be retrieved, always fsync the
>>> relay log file when rotating to a new file, by this way, we can be sure
>>> that only the last relay log file can be corrupted, so there's no need
>>> to retrieve logs before the events in the last relay log.
>>>       
>> Even though this is an improvement when the slave is restarted, 
>> I think we do not need to fix this now.
>>
>> Motivation:
>> - We already have the other code tested and in custom build
>> - The recovery mechanism will only execute when there is slave crash,
>>   so this optimization is not that useful
>>     
>
> If my understanding is correct, the recovery mechanism is executed evert
> time the slave is restarted, it does not detect for possible crashes, I
> also mentioned this in previous comments. But I agree that if we only
> run the recovery when we detected crashes, then the improvement to
> reduce log events to retrieve is not that necessary.
>   
Let's define restart.

restart = when the mysqld is started.
So if this is done manually, the user may disable the parameter.

restart != when the user runs the command "start slave".
So this operation does not trigger the recovery process.

For now, it does not detected a "normal shutdown and startup" from a "crash
and startup". This is a new feature proposed in WL#4621

Most likely I will have a draft implementation on Monday of this new
feature.
However, Lars said that it should be pushed only to 6.1.
It is up to you. Your "wishes is my command".
>   
>> - The better recovery mechanism (WL#4621) can be implemented later.
>>
>> /L
>>
>>
>>     
>>> Alfranio Correia wrote:
>>>       
>>>> #At
> file:///home/acorreia/workspace.sun/playground.mysql/mysql-5.0.68-custom_build/
>>>>
>>>>  2705 Alfranio Correia	2008-10-29
>>>>       Introduced a recovery mechanism that throws away relay-log.bin*
> retrieved
>>>>       from a master in case of a crash and updates the master.info based
> on
>>>>       the relay.info. This is done because such files may be corrupted
> after
>>>>       a crash. We are assuming that relay.info is fsynced per
> transaction.
>>>>       See BUG#40337.
>>>>         
>
>   

Cheers.