[pgpool-general: 6566] Pgpool Info Required

[Lakshmi Raghavendra]

Hi,

   It would be of a great help if someone helps me out with the below
queries, as am planning to use it in our production environment. Replies @
the earliest would be highly appreciated.

1. In case of failure on the master postgres, "failover_command" is being
executed.
However, In a 3 node cluster, when the master (node-0) goes down
failover_command is run against the node-1 (auto selection by pgpool). But
if this fails, there is no primary elected and also the following
follow_master_command is also not run.
Is there any way, we could configure the failover_command to run on node -2
, if it wasn't successful on node-1 ?

2.  Failover_command / follow_master_command is run only in case of primary
postgres failure. For some reason if a end-user wanted to switch his
primary postgres node from node-0 to node-1 in a 3-node pgpool cluster
(without any failures on node-0 ),
Does pgpool support any command which will internally do a combination of
failover_command( to make new node-1 as primary postgres )+
follow_master_command on the intended slaves ?

3. As per my understanding, VIP helps us to  always point to the primary
postgres. Thus any application which is accessing postgres  via VIP will
always be highly available. In my application due to some unknown reason,
when VIP is configured, the application's APIs stops working. Hence as a
workaround, I have chosen to maintain /etc/hosts entries of the primary
postgres on all my nodes and recover.conf / any one who would want to
access the master, would basically access with the name present here.
Please let me know if this serves the purpose or am I missing something
here.

4. When the postgres on master / slave comes up after a failure , is there
any script which could be run by pgpool to get it in sync with the new
master ?
I referred the documentation :
http://www.pgpool.net/docs/latest/en/html/runtime-config-failover.html ,which
says when a postgres node gets attached to pgpool failback_command will be
executed, but I never see the command being triggered by  pgpool when the
postgres server is back and running.
Kindly let me know how I can achieve this


5. In the pgpool logs, I see a line as below :

 2019-05-08T06:17:35+00:00  r connection request[14251]: [403-1] 2019-05-08
06:17:35: pid 14251: LOG:  failback event detected
2019-05-08T06:17:35+00:00 r connection request[14251]: [403-2] 2019-05-08
06:17:35: pid 14251: DETAIL:  restarting myself

Is it usual to see this in the log ?


Please let  me know.

Thanks in Advance !
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