[pgpool-general: 6478] Re: pgpool-II does nothing when slave node goes down

[Dmitry Medvedev]

Thnx for reply. I have some questions.

Question #1: failover script when stand-by fail.

In pgpool.conf there is parameter
failover_command = '' # Executes this command at failover
But there is no indication what exactly fail means - fail of master-server
or fail of stand-by server?
You wrote "When the standby is stopped, pgpool tries to reconnect x times
... then it does the failover script..." Where in pgpool.conf you defined
this script?

Question #2: you wrote "... it detaches the standby".
I did exactly the same setting as you wrote, but pgpool stil showing
stand-by as "up" meanwhile it is "down".
Mayby there is some parameter which exactly tells that stand-by MUST be
detached when it fails?

Question #3: you wrote "I  also put the parameter failover_on_backend_error
= 'off' "
Why? If "off" than when master fail occurs - no stand-by promotes. Or I
wrong?

вт, 26 мар. 2019 г. в 23:16, Pierre Timmermans <ptim007 at yahoo.com>:

> Hi Dimitri
>
> Did you set-up the health checks ?
>
> In my pgpool config I have the following parameters related to the health
> checks
>
> health_check_period = 10
> health_check_timeout = 10
> health_check_user = 'hcuser'
> health_check_password = 'hcuser'
> health_check_database = 'postgres'
> health_check_max_retries = 5
> health_check_retry_delay = 1
>
> I  also put the parameter
>
> failover_on_backend_error = 'off'
>
> And I created the user hcuser on the postgres database
>
> When the standby is stopped, pgpool tries to reconnect x times (depending
> on health_check_max_retries parameter) then it does the failover script
> (the script does not have to do something because it is not the primary
> failing) and it detaches the standby. When the standby is started again,
> pgpool does a failback script (I do nothing in this script) and then it
> attaches the standby again
>
> I believe that if you don't set-up the health-checks pgpool does not
> detach the standby when it fails (not sure if it is as-designed or not)
>
> Pierre
>
>
> On Tuesday, March 26, 2019, 3:58:52 PM GMT+1, Dmitry Medvedev <
> dm.dm.medvedev at gmail.com> wrote:
>
>
> Hello to everyone.
>
> A couple of days I've spent trying to understand how pgpool-II works.
> Tell me, please, principle of operation when slave node goes down.
> I've read tons of manuals and when master node in my test cluster goes
> down (or master's network interface goes down) - pgpool does failover
> actions. Everything is OK and works as expected.
> But when slave node goes down - pgpool does nothing at all and I receive
> such answer
>
> test=# show pool_nodes;
>  node_id |  hostname   | port | status | lb_weight |  role  | select_cnt |
> load_balance_node | replication_delay | last_status_change
>
> ---------+-------------+------+--------+-----------+--------+------------+-------------------+-------------------+---------------------
>  0       | 172.28.30.6 | 5434 | up     | 0.500000  | master | 3          |
> true              | 0                 | 2019-03-26 17:04:12
>  1       | 172.28.30.7 | 5434 | up     | 0.500000  | slave  | 0          |
> false             | 0                 | 2019-03-26 17:04:12
> (2 rows)
>
>
> At the same time slave node is completely down. Not "up"! select * from
> pg_stat_replication showing (0 rows)
>
> Why does pgpool-II does nothing when slave node goes down and how I can
> change it?
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