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From:Rick James Date:September 8 2008 7:45pm
Subject:RE: mysql Replication is too slow
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12:00-12:10:  do transaction (or ALTER or ...) that takes 10 minutes
12:10:  it replicates to slave and starts running there (Behind=10 min)
12:18:  do something quick on master, and replicate it.
12:20:  long thing finishes on slave  (just before finishing, Behind=20
min <-- sort of a lie)
12:20:  next query starts  (Behind=2 min <-- more realistic)

 
Rick James
MySQL Geeks - Consulting & Review

 

> -----Original Message-----
> From: Marcus Bointon [mailto:marcus@stripped] 
> Sent: Monday, September 08, 2008 12:21 PM
> To: Rick James
> Cc: Timo; replication@stripped
> Subject: Re: mysql Replication is too slow
> 
> On 8 Sep 2008, at 18:33, Rick James wrote:
> 
> > * Slave hardware should be at least as powerful as master.
> 
> I find this really isn't a problem. I run a slave with much less CPU  
> and disk, and it has no trouble keeping up because it's not 
> having to  
> do all the other things that the master does. It does lag 
> when I post  
> big transactions, but that's mainly due to a lack of speed on the  
> master, not the slave.
> 
> > * When there are long-running queries Seconds_Behind_Master lies,  
> > but you say it is consistently > 300 sec?
> 
> It certainly shouldn't be consistently behind whatever you do. The  
> only way I can think of that happening is if you often run  
> transactions that take about 10 minutes to run, in which case 
> you will  
> often be in that state, as transactions do not get replicated until  
> they commit (so the slaves never have to do rollbacks).
> 
> Marcus
> -- 
> Marcus Bointon
> Synchromedia Limited: Creators of http://www.smartmessages.net/
> UK resellers of info@hand CRM solutions
> marcus@stripped | http://www.synchromedia.co.uk/
> 
> 
> 
Thread
mysql Replication is too slowTimo8 Sep
  • RE: mysql Replication is too slowRick James8 Sep
    • Re: mysql Replication is too slowMarcus Bointon8 Sep
      • RE: mysql Replication is too slowRick James8 Sep
        • ConsultingDatabase System17 Sep
          • RE: ConsultingRick James17 Sep
            • RE: ConsultingDatabase System17 Sep
              • Re: ConsultingMarcus Bointon17 Sep