[pgpool-hackers: 3328] [proposal] New feature: auto failback of stancby node

Takuma Hoshiai hoshiai at sraoss.co.jp
Wed May 22 17:13:08 JST 2019

Hi all,

I suggest new feature of auto failback for Pgpool-II 4.1.

Now, pgpool execute backend degeneration at tempolary network error or query's error response or etc.
So standby node of streaming replication is degenerated by pgpool, even if replication 
between primary and standby nodes is no problem. In this case, pgpool set 'down' status,
but postgres's replication is continuing normally.
But User need to attached to pgpool manually, in order to do load balance by pgpool again for standby node.

I attached a patch of 'auto failback'. This feature use "replication_state" added for pool_worker_process in 4.1.
And valid if auto_failback is on. If worker process find node which replication_status is 
'streaming' and backend_status is 'down', worker_process request failback like pcp_attach_node.

Comments and suggestions are welcome.

Best regards,
Takuma Hoshiai <hoshiai at sraoss.co.jp>
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