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From:Sasha Pachev Date:February 14 2001 8:53pm
Subject:Re: Replication Bug in 3.23.33
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On Wednesday 14 February 2001 12:58, Matt Hahnfeld wrote:
>Wow, that was fast!  Thanks!!!!!!

We mean what we say - the better the bug report, the quicker the fix :-) 

>
>--Matt
>
>On Wed, 14 Feb 2001, Sasha Pachev wrote:
>
>> On Wednesday 14 February 2001 09:19, Matt Hahnfeld wrote:
>> >After downgrading to 3.23.30, replication worked fine without the problem
>> >posted below.  This appears to be a bug in the newest version (3.23.33)
>> >only.
>> >
>> >The failed tests were run under mysql-3.23.33-pc-linux-gnu-i686 (binary
>> >distribution).
>> >
>> >The same tests succeeded under mysql-3.23.30-gamma-pc-linux-gnu-i686
>> >(binary distribution) with no problems.
>> >
>> >---------- Forwarded message ----------
>> >Date: Tue, 13 Feb 2001 14:33:47 -0500 (EST)
>> >From: Matt Hahnfeld <hahnfld@stripped>
>> >To: mysql@stripped
>> >Subject: Strange Replication Problem in 3.23.33 (bug?)
>> >
>> >I set up two MySQL servers to run in a failover configuration.  Because
>> >queries will only ever be submitted to one server at a time, I decided to
>> >use a makeshift two-way replication scheme under MySQL as descibed in
>> >the MySQL manual.
>> >
>> >First server (wallace) has this:
>> >--------------------------------
>> >server-id=1
>> >log-bin
>> >master-host=gromit
>> >master-user=repl
>> >master-password=<password>
>> >log-slave-updates
>> >--------------------------------
>> >
>> >Second server (gromit) has this:
>> >--------------------------------
>> >server-id=2
>> >log-bin
>> >master-host=wallace
>> >master-user=repl
>> >master-password=<password>
>> >log-slave-updates
>> >--------------------------------
>> >
>> >I started by mirroring both data directories.  Then I started both servers
>> >and all looked fine.  Logs indicate no errors.  When I inserted some
>> >data on wallace, gromit replicated them just fine.  But when I tried to
>> >insert data on gromit, wallace never got the changes.  The weird thing is,
>> >no real errors appeared in the logs.
>> >
>> >Then I did a "SHOW SLAVE STATUS" on wallace and saw "Skip_counter" was
>> >set to 4294967295!!!  Strange, I thought, so I ran "STOP SLAVE", "SET
>> >SQL_SLAVE_SKIP_COUNTER=0", and "START SLAVE" on wallace.  Suddenly
>> >changes made on gromit were reflected on wallace.
>> >
>> >But then I tried to insert data on wallace again and the same thing
>> >happened.  This time gromit never got the changes.  When I ran "SHOW SLAVE
>> >STATUS" on gromit, it indicated 4294967293.  To get it to work, I had to
>> >run "SET SQL_SLAVE_SKIP_COUNTER=0" on gromit.
>> >
>> >I just don't get it...  Why are the skip counters being reset to thse
>> >crazy high numbers?
>>
>> Thanks for the bug report. The problem is a bug in the code that skips 
events
>> when it sees a log entry with the same server id - something that can only
>> happen in the bi-directional replicaiton setup. Fix:
>>
>> --- 1.85/sql/slave.cc   Sat Jan 27 15:33:30 2001
>> +++ edited/slave.cc     Wed Feb 14 12:35:34 2001
>> @@ -849,7 +849,8 @@
>>
>>        mi->inc_pos(event_len);
>>        flush_master_info(mi);
>> -      --slave_skip_counter;
>> +      if(slave_skip_counter)
>> +        --slave_skip_counter;
>>        delete ev;
>>        return 0;                                        // avoid infinite
>> update loops
>>      }
>>
>>
>>
>> --
>> MySQL Development Team
>>    __  ___     ___ ____  __
>>   /  |/  /_ __/ __/ __ \/ /   Sasha Pachev <sasha@stripped>
>>  / /|_/ / // /\ \/ /_/ / /__  MySQL AB, http://www.mysql.com/
>> /_/  /_/\_, /___/\___\_\___/  Provo, Utah, USA
>>        <___/
>>
>>

-- 
MySQL Development Team
   __  ___     ___ ____  __ 
  /  |/  /_ __/ __/ __ \/ /   Sasha Pachev <sasha@stripped>
 / /|_/ / // /\ \/ /_/ / /__  MySQL AB, http://www.mysql.com/
/_/  /_/\_, /___/\___\_\___/  Provo, Utah, USA
       <___/                  
Thread
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  • Re: DBI - basic questionColin McKinnon25 Mar
  • Re: Replication Bug in 3.23.33Sasha Pachev14 Feb
Re: Replication Bug in 3.23.33Sasha Pachev14 Feb