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From: Ron Johnson <ronljohnsonjr@gmail.com>
Date: Mon, 7 Oct 2024 23:30:05 -0400
Message-ID: <CANzqJaD5xa=5GSQ36R-c_i6kjSVtiA7S9LbCs_RaEBUE4STS9g@mail.gmail.com>
Subject: Re: Load balancing of write queries among health-checked nodes
To: "pgsql-generallists.postgresql.org" <pgsql-general@lists.postgresql.org>
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On Mon, Oct 7, 2024 at 11:04=E2=80=AFPM <me+postgres@kotovalexarian.com> wr=
ote:

> Hello. I have a PostgreSQL high availability cluster with Pgpool-II, but =
I
> don't use the virtual IP feature so my clients don't know which node to
> send queries to. DNS round-robin is not a solution because it can't
> distinguish between healthy and dead nodes.
>
> I thought about having a Pgpool-II instance on each client (client
> Pgpool-II -> cluster Pgpool-II -> PostgreSQL), but AFAIK it can't
> distribute write queries. I also know that libpq may have multiple nodes =
to
> connect, but I need an advanced health check because a node may have
> connectivity but be separated from the whole cluster so it must be
> considered dead.
>

Isn't that multi-master clustering?

--=20
Death to <Redacted>, and butter sauce.
Don't boil me, I'm still alive.
<Redacted> crustacean!

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<div dir=3D"ltr"><div dir=3D"ltr">On Mon, Oct 7, 2024 at 11:04=E2=80=AFPM &=
lt;<a href=3D"mailto:me%2Bpostgres@kotovalexarian.com">me+postgres@kotovale=
xarian.com</a>&gt; wrote:<br></div><div class=3D"gmail_quote"><blockquote c=
lass=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px soli=
d rgb(204,204,204);padding-left:1ex">Hello. I have a PostgreSQL high availa=
bility cluster with Pgpool-II, but I don&#39;t use the virtual IP feature s=
o my clients don&#39;t know which node to send queries to. DNS round-robin =
is not a solution because it can&#39;t distinguish between healthy and dead=
 nodes.<br>
<br>
I thought about having a Pgpool-II instance on each client (client Pgpool-I=
I -&gt; cluster Pgpool-II -&gt; PostgreSQL), but AFAIK it can&#39;t distrib=
ute write queries. I also know that libpq may have multiple nodes to connec=
t, but I need an advanced health check because a node may have connectivity=
 but be separated from the whole cluster so it must be considered dead.<br>=
</blockquote><div><br></div><div>Isn&#39;t that multi-master clustering?</d=
iv><div><br></div></div><span class=3D"gmail_signature_prefix">-- </span><b=
r><div dir=3D"ltr" class=3D"gmail_signature"><div dir=3D"ltr">Death to &lt;=
Redacted&gt;, and butter sauce.<div>Don&#39;t boil me, I&#39;m still alive.=
<br><div><div>&lt;Redacted&gt; crustacean!</div></div></div></div></div></d=
iv>

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