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From:He Zhenxing Date:February 16 2009 9:23am
Subject:Re: bzr commit into mysql-6.0-rpl branch (alfranio.correia:2810)
Bug#40337
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Alfranio Correia wrote:
> He Zhenxing wrote:
> 
> Thank you. I already added this comment in the code but I
> will also add it to the commit message.
> 

Great! Thank you!

> Cheers.
> 
> > Hi Alfranio,
> >
> > Patch approved, I only have some one comment regarding the commit
> > message.
> >
> > Alfranio Correia wrote:
> >   
> >> #At
> file:///home/acorreia/workspace.sun/repository.mysql/bzrwork/bug-40337/mysql-6.0-rpl/
> based on revid:luis.soares@stripped
> >>
> >>  2810 Alfranio Correia	2009-02-13
> >>       BUG#40337  Fsyncing master and relay log to disk after every event is
> too slow
> >>             
> >>       The fix proposed in BUG#35542 and BUG#31665 introduces a performance
> issue
> >>       when fsyncing the master.info, relay.info and relay-log.bin* after #th
> events.
> >>       Although such solution has been proposed to reduce the probability of
> corrupted
> >>       files due to a slave-crash, the performance penalty introduced by it
> has
> >>       made the approach impractical for highly intensive workloads.
> >>             
> >>       In a nutshell, the option --syn-relay-log proposed in BUG#35542 and
> BUG#31665
> >>       simultaneously fsyncs master.info, relay-log.info and relay-log.bin*
> and
> >>       this is the main source of performance issues.
> >>             
> >>       This patch introduces new options that give more control to the user
> on
> >>       what should be fsynced and how often:
> >>         1) (--sync-master-info, integer) which syncs the master.info after
> #th event;
> >>         2) (--sync-relay-log, integer) which syncs the relay-log.bin* after
> #th
> >>       events.
> >>         3) (--sync-relay-log-info, integer) which syncs the relay.info after
> #th
> >>         transactions.
> >>             
> >>       To provide both performance and increased reliability, we recommend
> the following
> >>       setup:
> >>         1) --sync-master-info = 0 eventually the operating system will fsync
> it;
> >>         2) --sync-relay-log = 0 eventually the operating system will fsync
> it;
> >>         3) --sync-relay-log-info = 1 fsyncs it after every transaction;
> >>             
> >>         Notice, however, that the previous setup does not reduce the
> probability of
> >>       corrupted master.info and relay-log.bin*. To overcome the issue, this
> patch also 
> >>       introduces a recovery mechanism that right after restart throws away
> relay-log.bin* 
> >>       retrieved from a master and updates the master.info based on the
> relay.info:
> >>     
> >
> > I think it's better to state clear that the recovery mechanisam can only
> > recover the incorrect binlog file and position in master.info, if other
> > informations (host, port password, etc) are corrupted or incorrect, then
> > this recovery mechanism will fail to work.
> >
> >   
> >>         4) (--relay-log-recovery, boolean) which enables a recovery
> mechanism that
> >>         throws away relay-log.bin* after a crash.
> >>             
> >>         So, it is advisable to setup: --syn-relay-log-info = 1.
> >>     
> >
> > [snip]
> >
> >
> >   

Thread
bzr commit into mysql-6.0-rpl branch (alfranio.correia:2810) Bug#40337Alfranio Correia13 Feb
  • Re: bzr commit into mysql-6.0-rpl branch (alfranio.correia:2810)Bug#40337He Zhenxing16 Feb
    • Re: bzr commit into mysql-6.0-rpl branch (alfranio.correia:2810)Bug#40337Alfranio Correia16 Feb
      • Re: bzr commit into mysql-6.0-rpl branch (alfranio.correia:2810)Bug#40337He Zhenxing16 Feb