Re: Invalid data read from synchronously replicated hot standby

[martin.kamp.jensen@xxxxxxxxxxxxxxxxxxxxxx]

Sameer Kumar <sameer.kumar@xxxxxxxxxx> wrote
on 04/21/2016 13:56:52:

> From: Sameer Kumar <sameer.kumar@xxxxxxxxxx>
> To: Martin Kamp Jensen/DK/Schneider@Europe, pgsql-general@xxxxxxxxxxxxxx
> Date: 04/21/2016 14:00
> Subject: Re:  Invalid data read from
synchronously 
> replicated hot standby
> 
> 

> On Thu, 21 Apr 2016 04:05 , <martin.kamp.jensen@xxxxxxxxxxxxxxxxxxxxxx>
wrote:
> Hi, 
> 
> We are getting invalid data when reading from a synchronously 
> replicated hot standby node in a 2-node setup. To better understand
> the situation, we have created a document that provides an overview.
> We are hoping that someone might be able to confirm whether or not
> the setup makes sense, i.e., whether we are using PostgreSQL 
> correctly and experiencing a bug, or if we are using PostgreSQL incorrectly.
> 
> Link to document that contains a step-by-step description of the situation:
> https://docs.google.com/document/d/1MuX8rq1gKw_WZ-
> HVflqxFslvXNTRGKa77A4NHto4ue0/edit?usp=sharing 
> 
> 
> 
> 
> 
> If the setup is sane (and expected to work), we will work on setting
> up a minimal reproduce that avoids our complete system. We are 
> thinking that a scripted Ansible/Vagrant setup makes sense. 
> 
> I am not sure if it is because of that but you are on an old patch.
> Upgrade to latest (I guess 9.1.21).

I have reproduced the issue on 9.1.20 which is the
latest version for Debian 6 (yes, I know, old stuff).

In the mean time, we are preparing a new platform
on 9.5.2 where I have not been able to reproduce the issue (however, we
have introduced a lot of changes besides upgrading PostgreSQL). I would
have liked to be able to come up with a minimal reproduce to be able to
reason about the issue but I guess we will not pursue that for now.

> 
> Once you have upgraded, re-create the stand by from scratch using
a 
> basebackup and then see if the error is still there.
> 
> 
> Best regards, 
> Martin 
> -- 
> --
> Best Regards
> Sameer Kumar | DB Solution Architect 
> ASHNIK PTE. LTD.
> 101 Cecil Street, #11-11 Tong Eng Building, Singapore
069 533
> T: +65 6438 3504 | M: +65 8110
0350 | www.ashnik.com
> 
> ______________________________________________________________________
> This email has been scanned by the Symantec Email Security.cloud service.
> ______________________________________________________________________