Re: [PATCH] add concurrent_abort callback for output plugin

On 30.03.21 09:39, Ajin Cherian wrote:
> Where do you suggest this be documented? From an externally visible 
> point of view, I dont see much of a surprise.

If you start to think about the option of committing a prepared 
transaction from a different node, the danger becomes immediately 
apparent:  A subscriber doesn't even know that the transaction is not 
complete.  How could it possibly know it's futile to COMMIT PREPARE it? 
  I think it's not just surprising, but outright dangerous to pretend 
having prepared the transaction, but potentially miss some of the changes.

(Essentially: do not assume the ROLLBACK PREPARED will make it to the 
subscriber.  There's no such guarantee.  The provider may crash, burn, 
and vanish before that happens.)

So I suggest to document this as a caveat for the prepare callback, 
because with this patch that's the callback which may be invoked for an 
incomplete transaction without the output plugin knowing.

Regards

Markus