[pgpool-general: 3456] Re: Questions about getting pgpool to handle failover more smoothly

Reuven M. Lerner reuven at lerner.co.il
Wed Feb 4 21:51:57 JST 2015

Hi, Tatsuo.  First and foremost, thanks so much for your work on 
pgpool-II.  I'm appreciative and impressed!

You wrote:

> I am not familiar with repmgr but I guess pgpool-II is confused by
> being taken over the task of failover and promotion by repmgr.

That's quite possible.

> To let pgpool-II properly work, you need to let pgpool-II handle
> faiover and promotion.

Ignoring the use of repmgr (since I don't think that it's connected), 
I'm wondering whether it's normal for pgpool-II to reset existing 
connections when one of the nodes fails.  From the documentation, this 
would appear to be the case:

>  When a failover is performed, pgpool kills all its child processes,
>  which will in turn terminate all active sessions to pgpool. Then
>  pgpool invokes the failover_command and waits for its
>  completion. After this, pgpool starts new child processes and is
>  ready again to accept connections from clients.

So it sounds like no matter how I do the replication, pgpool will reset 
all incoming sessions.  Is this the case?  And if so, why?

I know that most clients can handle a reset like this, but I'm just 
curious to know why pgpool can't continue to service the incoming 
connections, and shield the failover from the outside world.


Reuven M. Lerner, PhD -- Web development, consulting, and training
Mobile: +972-54-496-8405 * US phone: 847-230-9795
http://lerner.co.il * Skype / WeChat: ReuvenLerner * @reuvenmlerner

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