[Pgpool-general] procedures to reboot a node

[Marc G. Fournier]

On Mon, 4 May 2009, Tatsuo Ishii wrote:

> If pgpool continues to accept queries while one of PostgreSQL reboots,
> pgpool will automatically disconnects the database node. But pgpool
> does not save the queries while the node is down. So you need to
> resync the node explicitly. There are two options:

Have you thought of using something lightweight, like sqlite, to dump the 
queries into a queue and process those through to the down-node after it 
comes back up again?

> 1) Shutdown pgpool and all DB nodes. Physically copy the one of the
>   database cluster into the rebooted node. Start all the db nodes,
>   and finally start pgpool. With this procedure you don't need to set
>   up online recovery.

Ouch, for a *very* large database, that could be painful, no? :)

> 2) Setup online recovery. Stop the DB node you want to resync if it
>   does not already stop. Use pcp_recovery_node to resync the
>   node. After recovery, the node will automatically start.

Okay, so while in recovery, what happens?  The 'main node' continues to 
run fine while the recovery node is being recovered, and once finished, 
pgpool will resume using both nodes?

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Marc G. Fournier           Hub.Org Networking Services (http://www.hub.org)
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