Re: PG wire protocol question

On Sat, 14 May 2016 21:58:48 +0200, Boszormenyi Zoltan <zboszor(at)pr(dot)hu>
wrote:

>Hi,
>
>it was a long time I have read this list or written to it.
>
>Now, I have a question. This blog post was written about 3 years ago:
>https://aphyr.com/posts/282-jepsen-postgres
>
>Basically, it talks about the client AND the server as a system
>and if the network is cut between sending COMMIT and
>receiving the answer for it, the client has no way to know
>whether the transaction was actually committed.
>
>The client connection may just timeout and a reconnect would
>give it a new connection but it cannot pick up its old connection
>where it left. So it cannot really know whether the old transaction
>was committed or not, possibly without doing expensive queries first.
>
>Has anything changed on that front?
>
>There is a 10.0 debate on -hackers. If this problem posed by
>the above article is not fixed yet and needs a new wire protocol
>to get it fixed, 10.0 would be justified.

It isn't going to be fixed ... it is a basic *unsolvable* problem in
communication theory that affects coordination in any distributed
system. For a simple explanation, see

https://en.wikipedia.org/wiki/Two_Generals'_Problem

>Thanks in advance,
>Zoltán Böszörményi

George