Re: Invalid data read from synchronously replicated hot standby

On Wed, May 11, 2016 at 5:44 AM,
<martin(dot)kamp(dot)jensen(at)schneider-electric(dot)com> wrote:

>> 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

Please include such information in your post or as an attachment.
Who knows whether that link will still be usable and unchanged 20
years from now?

>> If the setup is sane (and expected to work),

I didn't see anywhere that you correctly handled WAL in setting up
your standby. I am not surprised by there being corruption,
including duplicate keys in a unique index. You might try -x or -X
when you run pg_basebackup, or use archiving. Whatever you do, do
NOT delete the backup_label file!

> 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).

We would need a lot more detail to be able to even guess at whether
you have actually solved the flaws in your process or have just
been lucky so far.

--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company