On 8/29/2012 9:27 AM, David TECHER wrote:
> Hi,
>
> I have to do a maintenance on a replicated table. We found that a
> foreign key have been added on the replicated table.
>
> Instead of using DDL execute script, I am used to do
>
> - removing table from replication
>
> - doing my altered queries
>
> - putting back table into replication.
>
> Since the replicated table has a small size and since my altered query is
>
> alter table ... add constraint ... foreign key  ... references ....(....);
>
> I asked myself if the 3 steps above are mandatory ( or "DDl execute
> script")  or if I can execute my altered query directly?

It depends on the Slony version you are using.

Since version 2.0 DDL "may" be executed safely against any node in the 
cluster. There is no problem with the system catalog any more, like 
prior to 2.0. But it should be obvious that certain changes can lead to 
problems later on. Having extra columns on a master for example would 
break replication while extra columns on a subscriber are no problem, as 
long as you never move the set to it. Foreign keys are NOT enforced 
during replication, so additional FK on a subscriber would eventually 
lead to trouble when you move set or make that node a stand alone DB.


Jan

-- 
Anyone who trades liberty for security deserves neither
liberty nor security. -- Benjamin Franklin