[pgpool-general: 6313] Re: load_balance_node column value keeps switching in "show pool_nodes" output
Bo Peng
pengbo at sraoss.co.jp
Tue Nov 27 16:25:29 JST 2018
Hi,
On Tue, 27 Nov 2018 12:00:42 +0800
Mike Yeap <wkk1020 at gmail.com> wrote:
> Hello! I noticed the value in the load_balance_node column keeps switching
> between "true" and "false" for both nodes, even there's no change in the
> Postgres's availability.
>
> Is it indicating any configuration problems?
No. It's normal.
"load_balance_node" means the node which is selected for load balancing.
When a session starts, Pgpool-II will select one node as load_balance_node.
At the next session, the load_balance_node may be changed.
You can control the probability of being selected as load_balance_node
by setting backend_weight.
> # pgpool.conf
> backend_hostname0 = 'hoopa-uat-1.sg.m-daq.net'
> backend_port0 = 5432
> backend_weight0 = 1
> backend_data_directory0 = '/var/lib/pgsql/11/data'
> backend_flag0 = 'ALWAYS_MASTER'
>
> backend_hostname1 = 'hoopa-uat-2.sg.m-daq.net'
> backend_port1 = 5432
> backend_weight1 = 1
> backend_data_directory1 = '/var/lib/pgsql/11/data'
> backend_flag1 = 'ALLOW_TO_FAILOVER'
>
> # output for "show pool_nodes"
> [postgres at hoopa-uat-1 data]$ psql -h hoopa-uat-pgpool-1.sg.m-daq.net -p
> 5432 -U postgres -c "show pool_nodes" postgres
> show pool_nodes
> node_id | hostname | port | status | lb_weight | role |
> select_cnt | load_balance_node | replication_delay | last_status_change
> ---------+--------------------------+------+--------+-----------+---------+------------+-------------------+-------------------+---------------------
> 0 | hoopa-uat-1.sg.m-daq.net | 5432 | up | 0.500000 | primary |
> 48 | true | 0 | 2018-11-27 11:54:06
> 1 | hoopa-uat-2.sg.m-daq.net | 5432 | up | 0.500000 | standby |
> 51 | false | 0 | 2018-11-27 11:54:06
> (2 rows)
>
> [postgres at hoopa-uat-1 data]$ psql -h hoopa-uat-pgpool-1.sg.m-daq.net -p
> 5432 -U postgres -c "show pool_nodes" postgres
> show pool_nodes
> node_id | hostname | port | status | lb_weight | role |
> select_cnt | load_balance_node | replication_delay | last_status_change
> ---------+--------------------------+------+--------+-----------+---------+------------+-------------------+-------------------+---------------------
> 0 | hoopa-uat-1.sg.m-daq.net | 5432 | up | 0.500000 | primary |
> 48 | false | 0 | 2018-11-27 11:54:06
> 1 | hoopa-uat-2.sg.m-daq.net | 5432 | up | 0.500000 | standby |
> 51 | true | 0 | 2018-11-27 11:54:06
> (2 rows)
>
>
> Thank you.
>
> Regards,
> Mike Yeap
--
Bo Peng <pengbo at sraoss.co.jp>
SRA OSS, Inc. Japan
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