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From:Jesper Wisborg Krogh Date:July 16 2013 12:25pm
Subject:Re: User-defined variables not working ONLY on first query in chained
replication
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Hi Matthew,

On 16/07/2013 21:21, Matthew Ward wrote:
> I've noticed a weird issue in our chained replication environment where when setting
> user-defined variables, the first time the variable is used in a session the value is
> NULL, but all uses thereafter work correctly.
<snip>
> The first time I run this insert, the value is correctly inserted in to master1 and
> its slave, master3 (as you'd expect). However, a NULL value is inserted into
> master3-slave1. However, if I run the INSERT a second time (just the insert, no
> re-declaration of the user-defined variable), the value is correctly inserted in to all
> three servers, so that the contents of test_table on the three servers looks as follows:
<snip>
> Is this a known issue in MySQL with chained replication like this, or have I
> discovered a bug?

Do you happen to have any table level replication filters? If so it 
sounds like you are affected by a bug that was fixed in 5.5.32 
(https://dev.mysql.com/doc/relnotes/mysql/5.5/en/news-5-5-32.html):

> *Replication:*Running the server with both the|--log-slave-updates| 
>
> <http://dev.mysql.com/doc/refman/5.5/en/replication-options-slave.html#option_mysqld_log-slave-updates>and|--replicate-wild-ignore-table|
> 
>
> <http://dev.mysql.com/doc/refman/5.5/en/replication-options-slave.html#option_mysqld_replicate-wild-ignore-table>options
> 
> in some cases caused updates to user variables not to be logged.

(Note: at least replicate-ignore-table is also triggering that bug).

Best regards,
Jesper Krogh
MySQL Support

Thread
User-defined variables not working ONLY on first query in chained replicationMatthew Ward16 Jul
  • Re: User-defined variables not working ONLY on first query in chainedreplicationJesper Wisborg Krogh16 Jul