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From:Jon Olav Hauglid Date:June 3 2011 10:57am
Subject:Re: bzr commit into mysql-trunk branch (jon.hauglid:3142) Bug#12585718
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On 06/01/2011 09:19 PM, Sergei Golubchik wrote:
> Hi, Jon!

Hello!

> On Jun 01, Jon Olav Hauglid wrote:
>>   3142 Jon Olav Hauglid	2011-06-01
>>        Bug#12585718 REPLICATION BREAKS WITH LARGE INDEX PREFIX ON UNIQUE INDEX
>
> What was the problem with the replication?
>
>>        Tentative patch for discussion purposes.
>>
>>        Before this patch, creating an index with a prefix longer than the
>>        maximum supported length only gave a warning for non-unique indexes
>>        but an error for unique indexes.
>>
>>        This patch changes the behavior for non-unique indexes so
>>        an ER_TOO_LONG_KEY error is reported in this case as well.
>
> This was the old MySQL behavior.
>
> Changed later to be a non-fatal error, as an index is only an
> optimization aid, and truncating it does not introduce an error.
> A unique index, on the other hand, is a constraint. DBMS should not
> automatically change it.
>
> But what does it have to do with replication?

It can be an issue for replication if master and slave have different 
configurations wrt index prefix length.

If it's a non-unique index, the slave can truncate the index (with just 
a warning) while the master accepts the index without truncation.

We're discussing the issue, which is why I didn't bother with a better 
commit message just yet :-)

--- Jon Olav Hauglid
Thread
bzr commit into mysql-trunk branch (jon.hauglid:3142) Bug#12585718Jon Olav Hauglid1 Jun
  • Re: bzr commit into mysql-trunk branch (jon.hauglid:3142)Bug#12585718Sergei Golubchik1 Jun
    • Re: bzr commit into mysql-trunk branch (jon.hauglid:3142) Bug#12585718Jon Olav Hauglid4 Jun