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