[pgpool-general: 6288] Re: load balance between hosts with same FQDN

[Tatsuo Ishii]

> Dear Mr. Ishii Sir ... and All
> I Really appreciate your response
> 
> On Sun, Nov 18, 2018 at 7:11 AM Tatsuo Ishii <ishii at sraoss.co.jp> wrote:
> 
>> Hi bino,
>>
>> My guess is,
>>
>> - Load balancing will work. DNS round robin will assign 10.10.10.1 or
>>   10.10.10.2 to Pgpool-II but it should work.
>>
>> - Health checking will not work. After health checking detects a fault
>>   of standby, it notices the Pgpool-II main process that
>>   replica.pgcluster.service.bino.inc' is down, then it detach standby
>>   1, even if remaining standby is healthy.
>>
>> - Streaming replication delay checking will not work. I will report
>>   the delay for 10.10.10.1 or 10.10.10.2 depending on the DNS round
>>   robin. So the result will not consistent.
>>
>> Best regards,
>> --
>> Tatsuo Ishii
>> SRA OSS, Inc. Japan
>> English: http://www.sraoss.co.jp/index_en.php
>> Japanese:http://www.sraoss.co.jp
>>
>>
>> well , Actualy health check and replication things I think will handled by
> patroni.
> In this scenario, I positioned pgpool-II only to split request Between
> SELECT and WRITE..
> Is that make sense ?

I am not familiar with Patroni. So I cannot answer this.

> Patroni will decide which one is Master and Replicas.
> 
> BTW, is there any documentation in using 3 PG-POOL with 3 Postgres host ?
> I just want that my user only see single hostname, but don't want 'single
> point of failure'.

There's a 3 Pgpool-II with 2 PostgreSQL example.
http://www.pgpool.net/docs/latest/en/html/example-cluster.html

I think you could easily extend this for 3 PostgreSQL configuration.

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp