pgpool Connections Distributions Among Nodes

On 01/29/2018 08:19 AM, Kumar, Virendra wrote:

Hi Gurus,

We have 4-node cluster (1 master and 3 hot standby). �We are using
pgpool as load balancer. We have an observation where if application
requests for 3 connections, pgpool connects to all 4 servers and I see 3
connections on each of them. I was expecting it have a total of 3
connections from either of 4 servers but I can easily see 12 connections
in all.

Can somebody shed some light on it.

Please let me know if you need more information.

I would say the contents of your config file at the least.

Regards,

Virendra

--
Adrian Klaver
adrian.klaver@aklaver.com

We have 4-node cluster (1 master and 3 hot standby). We are using pgpool
as load balancer. We have an observation where if application requests for
3 connections, pgpool connects to all 4 servers and I see 3 connections on
each of them. I was expecting it have a total of 3 connections from either
of 4 servers but I can easily see 12 connections in all.

Can somebody shed some light on it.

Please let me know if you need more information.

Hello,

Which version pgpool you are using?

How did you balance the reading by pgpool? Should all readings go to the
replicas? or reading goes to all nodes?

Regards,

Glauco Torres

Attached is config file.

[pgpool@usdf23v0550 ~]$ pgpool -v
pgpool-II version 3.7.1 (amefuriboshi)

Reading should go to all nodes.

Regards,
Virendra
From: Glauco Torres [mailto:torres.glauco@gmail.com]
Sent: Monday, January 29, 2018 11:53 AM
To: Kumar, Virendra
Cc: pgsql-general@postgresql.org
Subject: Re: pgpool Connections Distributions Among Nodes

We have 4-node cluster (1 master and 3 hot standby). We are using pgpool as load balancer. We have an observation where if application requests for 3 connections, pgpool connects to all 4 servers and I see 3 connections on each of them. I was expecting it have a total of 3 connections from either of 4 servers but I can easily see 12 connections in all.

Can somebody shed some light on it.

Please let me know if you need more information.

Hello,
Which version pgpool you are using?
How did you balance the reading by pgpool? Should all readings go to the replicas? or reading goes to all nodes?
Regards,
Glauco Torres

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We have 4-node cluster (1 master and 3 hot standby). We are using pgpool as load balancer. We have an observation where if application requests for 3 connections, pgpool connects to all 4 servers and I see 3 connections on each of them. I was expecting it have a total of 3 connections from either of 4 servers but I can easily see 12 connections in all.

Yes, that's an expected behavior.

Why?

When client A connects to pgpool, it connects to all PostgreSQL (a, b,
c, d). But actually pgpool sends query to one of them (in case load
balance node is primary) or two of them (in case load balance node is
not primary). Suppose it sends to a and b. Client A logs off, but
connections to a and b remain because of connection pooling. Client B
comes in. B uses c and d. The connections to c and d remain.

So eventually pgpool needs to connect to all backend anyway.

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