[imp] MySQL Question

[Didi Rieder]

Quoting Chuck Hagenbuch <chuck at horde.org>:

> Quoting Didi Rieder <adrieder at sbox.tugraz.at>:
> 
> > is it possible to run HORDE/IMP with mySQL in a two-way replication
> > setup?
> 
> I'm not sure. How do MySQL clients have to specially handle that? I'd think
> they would want to make it transparent to the programs using it...
> 

>From the MySQL FAQs:

Q: What issues should I be aware of when setting up two-way replication?

A: MySQL replication currently does not support any locking protocol between
master and slave to guarantee the atomicity of a distributed (cross-server)
update. In other words, it is possible for client A to make an update to
co-master 1, and in the meantime, before it propagates to co-master 2, client B
could make an update to co-master 2 that will make the update of client A work
differently than it did on co-master 1. Thus when the update of client A will
make it to co-master 2, it will produce tables that will be different from what
you have on co-master 1, even after all the updates from co-master 2 have also
propagated. So you should not co-chain two servers in a two-way replication
relationship, unless you are sure that you updates can safely happen in any
order, or unless you take care of mis-ordered updates somehow in the client code. 

So I wanted to know if I would meet the discussed problem when using a two-way
replication?

Second question (as alternative):
Would it be possible for a future HORDE to optionally redirect all wirtes to the
master, and distribute the reads among the slaves?

Didi

-- 
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Didi Rieder
adrieder at sbox.tugraz.at
PGPKey ID: 3431D0B0
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