Re: Synchronous commit behavior during network outage

On Tue, 2021-04-20 at 18:49 +0100, Ondřej Žižka wrote:
> tecmint=# select * from a; --> LAN on sync replica is OK
>   id
> ----
>    1
> (1 row)
> 
> tecmint=# insert into a values (2); ---> LAN on sync replica is DOWN and 
> insert is waiting. During this time kill the background process on the 
> PostgreSQL server for this session
> WARNING:  canceling the wait for synchronous replication and terminating 
> connection due to administrator command
> DETAIL:  The transaction has already committed locally, but might not 
> have been replicated to the standby.
> server closed the connection unexpectedly
>      This probably means the server terminated abnormally
>      before or while processing the request.
> The connection to the server was lost. Attempting reset: Succeeded.
> 
> tecmint=# select * from a;
>   id
> ----
>    1
>    2
> (2 rows)

It is well known that synchronous replication is sublect to that problem,
since it doesn't use the two-phase commit protocol.

What surprises me is that this is a warning.
In my opinion it should be an error.

Yours,
Laurenz Albe