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

[He Zhenxing]

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.

> - 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.
>