[pgpool-general: 3067] Re: Failover - new primary selection process?

jayknowsunix at gmail.com jayknowsunix at gmail.com
Mon Jul 28 20:00:37 JST 2014


Then, I hate to say it, Ishii-san, but your log message is a bit misleading. For instance, I always see a message during a failover where the standby claims, "I'm the oldest, so assuming the master role." So, maybe it should just "I have the lowest remaining node number, so I'm assuming the master role."  That wouldn't imply logic based on time, only sequences.

Sent from my iPad

> On Jul 28, 2014, at 3:20 AM, Tatsuo Ishii <ishii at postgresql.org> wrote:
> 
> No. Pgpool-II has no idea which server has been running longer.
> 
> Pgpool-II has no built-in logic to choose next
> to-be-primary-candidate. Which slave node will be promoted next time
> is completely depending on your failover script. In general most
> people specifies the candidate slave as the master node, which has the
> yonguest node number among live slave nodes (%m in failover script).
> Example: you have node 0 primary, node 1&2 standby.
> 
> 1) node 0 is down.
> 
> 2) node 1 is chosen as the next primary because it's the youngest live
> node (master).
> 
> 3) node 1 is down.
> 
> 4) node 2 is chosen as the next primary because it's the youngest live
> node (master).
> 
> Best regards,
> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese:http://www.sraoss.co.jp
> 
>> Hey jay, thank you for the replay.
>> Is this is a formal conclusion? Maybe the oldest is the one with the
>> smaller ID ?
>> 
>> 
>> 
>>> On Sun, Jul 27, 2014 at 2:50 PM, <jayknowsunix at gmail.com> wrote:
>>> 
>>> Guy,
>>> 
>>> I run a master with 2 slaves. During a failover, I always see the oldest
>>> slave promoted to master. So, the selection is based on the server which
>>> has been running longer.
>>> 
>>> --
>>> Jay
>>> 
>>> Sent from my iPad
>>> 
>>>> On Jul 27, 2014, at 3:48 AM, Guy Meler <melguy at gmail.com> wrote:
>>>> 
>>>> Hey :)
>>>> In master/slave mode, what is the algorithm for choosing the next
>>> available primary backend?
>>>> I want to make sure that if primary in site A goes down, than the next
>>> available primary is in the same site.
>>>> 
>>>> Thank you
>>>> 
>>>> _______________________________________________
>>>> pgpool-general mailing list
>>>> pgpool-general at pgpool.net
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>>> 


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