Thanks for your reply.

if the orig master is down say due to some hardware issue (for few
hours/days say), we have to get the system on the slave up (we accept the
loss of some N txn)

In this case, Is the following pseudcode correct. Assuming before crash of
master, my master was node:1 and slave node:2
   On the slave (node 2),
          a) i run failover command (failover (id=1, backup node = 2)
          b) Run drop node command of node (1)
   When the orig master is ready to be brought back in service can i re-use
the node (1) for it?
   if so , is it enough to run just the following 2 commands on the original
master
       store node (id = 1, event node = 2);
       store path (server=2, client=1, conninfo='connection info to node2')

On Tue, Feb 15, 2011 at 2:52 PM, Jan Wieck <JanWieck at yahoo.com> wrote:

> On 2/15/2011 2:44 PM, Jan Wieck wrote:
>
>> This is NOT possible given the Slony-I design.
>>
>> Slony-I is an asynchronous replication system. That means that changes
>> to the origin are replicated some time AFTER they have been committed.
>> That means that if the origin goes down unexpectedly, you have no chance
>> of knowing what changes did not propagate to the replica before it
>> crashed.
>>
>> The only way to solve this situation is to actually do a hard FAILOVER,
>> abandoning the old origin and rebuilding it from scratch.
>>
>> To illustrate, think about a simple foreign key constraint, t2.fk
>> references t1.pk. There currently are no rows in t2 referencing a
>> certain t1.pk, so node:1 will allow to DELETE it. Node:1 crashes before
>> the DELETE can propagate to node:2. You failover to node:2 and since it
>> still has the t1 row, it will happily allow you to INSERT references to
>> it into t1. Now you bring back node:1 and ... how exactly do you get the
>>
>
> into t2, of course.
>
>
>  two to agree what is right? Will you forcefully remove the rows, node:2
>> inserted into t2 or will you recreate the t1 row in node:1 so that the
>> INSERT's can propagate from node:2 to node:1?
>>
>>
>> Jan
>>
>>
>
> --
> Anyone who trades liberty for security deserves neither
> liberty nor security. -- Benjamin Franklin
>
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