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Re: Streaming Replication between PostGreSQL 9.2.2 on Red Hat andPostGreSQL 9.2.24 on Debian - Mailing list pgsql-general

From talk to ben
Subject Re: Streaming Replication between PostGreSQL 9.2.2 on Red Hat andPostGreSQL 9.2.24 on Debian
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Msg-id CAPE8EZ6owqxdJweh1LaWZ6vaU6StG90oaTBfL=Zz6ep9Juqw5Q@mail.gmail.com
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In response to Re: Streaming Replication between PostGreSQL 9.2.2 on Red Hat andPostGreSQL 9.2.24 on Debian  (Jonatan Evald Buus <jonatan.buus@cellpointmobile.com>)
Responses Re: Streaming Replication between PostGreSQL 9.2.2 on Red Hat andPostGreSQL 9.2.24 on Debian
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Hi,
  • Doing Streaming Replication between different minor version of PG is possible but not recommended [2]
  • Doing Streaming Replication between different OSes is not recommended pre ICU (pg10), please check you glibc versions. [1]

[1] https://www.postgresql.org/message-id/BA6132ED-1F6B-4A0B-AC22-81278F5AB81E@tripadvisor.com
[2] https://www.postgresql.org/docs/9.2/static/warm-standby.html (planning section)

Hoep this helps.

Cheers
Ben

2018-05-22 10:13 GMT+02:00 Jonatan Evald Buus <jonatan.buus@cellpointmobile.com>:
Thanks Ian, thank you for pointing out the obvious.
It appears that Debian's pg_dropcluster command had unexpected consequences.... you live, you pull out your hair in frustration and you learn.

I now have streaming replication working as we expected, can you confirm that my (somewhat unusual scenario?) shouldn't cause any problems?
Specifically:
- Using Streaming Replication between two PostGreSQL instances with different minor versions will work (9.2.2 on RHEL and 9.2.24 on Debian)
- Using Streaming Replication between two servers running different operating systems (RHEL 5.5 and Debian 8 / 9) will work

Greatly appreciate your insight

Cheers
Jona

On 21 May 2018 at 13:27, Ian Barwick <ian.barwick@2ndquadrant.com> wrote:
On 05/21/2018 07:18 PM, Jonatan Evald Buus wrote:
> Hi there,
>
> I'm trying to configure streaming replication between a Red Hat server
> running PostGreSQL 9.2.2 and a Debian server running PostGreSQL 9.2.24
> with Hot Standby enabled.
>
 > While the base backup works fine using /pg_basebackup/, I get the following
> errors with hot standby enabled on the Debian slave when starting PostGreSQL:

 > /WARNING:  WAL was generated with wal_level=minimal, data may be missing/
> /HINT:  This happens if you temporarily set wal_level=minimal without taking a new base backup./
> /FATAL:  hot standby is not possible because wal_level was not set to "hot_standby" on the master server/
> /HINT:  Either set wal_level to "hot_standby" on the master, or turn off hot_standby here/
>
> If I turn Hot Standby off on the Debian Slave I get the following errors:
 > /FATAL:  database system identifier differs between the primary and standby/
> /DETAIL:  The primary's identifier is 5940475598986796885, the standby's identifier is 6557962695089036503./

The standby clearly hasn't been cloned from the primary, otherwise the
identifiers would be the same. Are you sure the PostgreSQL instance
running on the standby is the one you backed up with pg_basebackup?


Regards

Ian Barwick

--
 Ian Barwick                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services



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