Andrew Sullivan <ajs at crankycanuck.ca> writes:
> On Tue, May 20, 2008 at 02:09:28PM +1000, Glen Edmonds wrote:
>> 
>> Here's my basic problem with slony and why I think it is not yet
>> "industrial strength":
>>  
>> Despite what the home page says, Slony is absolutely not a clustering
>> solution.  It is a replication solution.  For any database to have true
>> high availability (achievable 24/7 up time), it must have a clustering
>> solution.  Put simply, a cluster has these things:
>
> Well, I think this depends pretty heavily on whatever local definition of
> "cluster", "industrial", and "24/7 uptime" you have.
>
> It sounds like what you want is a multi-machine cluster of databases with
> multiple members in read/write mode, with some kind of failure detection
> that takes over transactions in the event of the loss of a cluster member. 

A base bit of the design rules this sort of thing out:
-----------------
1.3. What Slony-I is not

    * Slony-I is not a network management system.

    * Slony-I does not have any functionality within it to detect a
      node failure, nor to automatically promote a node to a master or
      other data origin.
-----------------

HA *requires* a set of functionality to evaluate these things, and
those things tend to be quite platform-specific.

PostgreSQL and Slony-I are both intended to be platform-agnostic,
which means that quite a bit of the apparatus necessary can't get
integrated into the project, at least, not tightly.
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