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From:Chris Knipe Date:February 28 2005 5:46pm
Subject:Re: two-way replication
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----- Original Message ----- 
From: <SGreen@stripped>
To: "Chris Knipe" <savage@stripped>
Cc: <mysql@stripped>
Sent: Monday, February 28, 2005 7:11 PM
Subject: Re: two-way replication

> "Chris Knipe" <savage@stripped> wrote on 02/28/2005 11:53:14 AM:
>> Hi,
>> Is two-way replication possible with MySQL 5.x?  Any good sites / docs
>> describing this type of setup?
>> --
>> Chris.
> By "two-way" replication, do you mean "changes to either database are
> synchronized to the other"? This is a dual-master situation and not yet
> supported by MySQL.  The problem is with cross-server locking. Right now
> (even with v5.0) MySQL does not know to lock a record on your "other"
> server to prevent someone over "there" from changing that record while you
> are editing it on "this" server. Same goes for inserts (auto_increment
> values are not coordinated) and deletes.
> Now, I have been monitoring the development lists on the MySQL Cluster and
> MySQL Federated lines and both are working on inter-server coordination
> but I have no idea if either of those products will fit your need.
> As of today, MySQL does support 1-way, and chained replication. There is
> no rule that prevents you from creating circular replication by making
> each server the "child" of the other. The danger with circular replication
> is that you need to ensure (by application-level logic, data partitioning,
> or any of other techniques) that insert collisions do not occur (no two
> new records get the same primary key from different servers) and that you
> can gracefully handle simultaneous updates (as they are not prevented at
> the server level).
> Search this list's and the other lists' archives (
> for some pretty clever workarounds to help stabilize circular replication.
> During your searches, you will find links to several books that are
> online, I highly recommend you read ALL of those links.

Thanks Shawn,

I will look into it as well as clustering.  I think clustering may solve my 
problems, I am not sure myself to be honest.

We basically operate a large WAN, and due to time critical queries on the 
databases (such as Radius AAA), I want to find a way to roll out multiple 
databases at strategic locations on the network.  The problem comes in that 
all these databases MUST handle INSERT, SELECT, UPDATE, and DELETE 
propperly, and migrate any changes through all the databases servers on the 
network (for now, it will just be 2, but I'm sure this will become more 

I have to admit, I haven't been following the MySQL developments too much 
since 4.x came out, so yes, I do have some reading to do.

Thanks again for your input.


two-way replicationChris Knipe28 Feb
  • Re: two-way replicationSGreen28 Feb
    • Re: two-way replicationChris Knipe28 Feb
  • Re: two-way replicationGleb Paharenko1 Mar