Re: Synchronous commit behavior during network outage

Hello Maksim,

I know your post [1]. That thread is why there we performed more tests 
(see another my email in this thread). We are trying to somehow 
implement RPO=0 solution using PostgreSQL. Knowing this... Would be 
possible to build RPO=0 solution with PostgreSQL?

Ondrej

On 20/04/2021 18:51, Maksim Milyutin wrote:
> Hi!
>
>
> This is a known issue with synchronous replication [1]. You might 
> inject into unmodified operation some dummy modification to overcome 
> the negative sides of such partially committing without source code 
> patching.
>
>
> On 20.04.2021 19:23, Aleksander Alekseev wrote:
>> Although it's unlikely that someone implemented
>> an application which deals with important data and "pressed Ctr+C" as
>> it's done in psql.
>
>
> Some client libraries have feature to cancel session that has similar 
> effect to "Ctrl+C" from psql after specified by client deadline 
> expiration [2]. Hence, this case might be quite often when application 
> interacts with database.
>
>
>> On Mon, Apr 19, 2021 at 10:13 PM Ondřej Žižka 
>> <ondrej.zizka@stratox.cz> wrote:
>>
>>  From the synchronous_commit=remote_write level and "higher", I would 
>> expect, that when the remote application (doesn't matter if flush, 
>> write or apply) would not be applied I would not receive a 
>> confirmation about the commit (even with a warning). Something like, 
>> if there is no commit from sync replica, there is no commit on 
>> primary and if someone performs the steps above, the whole 
>> transaction will not send a confirmation.
>
>
> The warning have to be accounted here and performed commit have not to 
> be treated as *successful*.
>
>
> 1. 
> https://www.postgresql.org/message-id/C1F7905E-5DB2-497D-ABCC-E14D4DEE506C%40yandex-team.ru
>
> 2. 
> https://www.postgresql.org/message-id/CANtu0ogbu%2By6Py963p-zKJ535b8zm5AOq7zkX7wW-tryPYi1DA%40mail.gmail.com
>
>