Content-Type: text/plain;
	charset=us-ascii
Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3776.700.51.11.1\))
Subject: Re: Built-in Raft replication
From: Andrey Borodin <x4mmm@yandex-team.ru>
In-Reply-To: <1798838.1744759182@sss.pgh.pa.us>
Date: Wed, 16 Apr 2025 09:07:28 +0500
Cc: Konstantin Osipov <kostja.osipov@gmail.com>,
 Greg Sabino Mullane <htamfids@gmail.com>,
 Nikolay Samokhvalov <nik@postgres.ai>,
 pgsql-hackers@lists.postgresql.org
Content-Transfer-Encoding: quoted-printable
Message-Id: <20FB597F-641F-48F8-8428-D8DDBA802D58@yandex-team.ru>
References: <Z_1Cq7JvabsFYjQo@ark>
 <CAKAnmmJxGHcQmzXqEQ-nppZjXyH7i5W_7Cz8JNMb2+6c5+D+og@mail.gmail.com>
 <CAM527d9+eGvdih1GxoPDJ2WYs6eitf39oNTxGxnCK1PgF=A8wg@mail.gmail.com>
 <1798838.1744759182@sss.pgh.pa.us>
To: Tom Lane <tgl@sss.pgh.pa.us>
Archived-At: <https://www.postgresql.org/message-id/20FB597F-641F-48F8-8428-D8DDBA802D58%40yandex-team.ru>
Precedence: bulk


> On 16 Apr 2025, at 04:19, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>=20
> feebly, and seems to have a bus factor of 1.  Another example is the
> Spencer regex engine; we thought we could depend on Tcl to be the
> upstream for that, but for a decade or more they've acted as though
> *we* are the upstream.

I think it's what Konstantin is proposing. To have our own Raft =
implementation, without dependencies.

IMO to better understand what is proposed we need some more description =
of proposed systems. How the new system will be configured? initdb and =
what than? How new node joins cluster? What is running pg_rewind when =
necessary?

Some time ago Peter E proposed to be able to start replication atop of =
empty directory, so that initial sync would be more straightforward. And =
also Heikki proposed to remove archive race condition when choosing new =
timeline. I think this steps are gradual movement in the same direction.

My view is what Konstantin wants is automatic replication topology =
management. For some reason this technology is called HA, DCS, Raft, =
Paxos and many other scary words. But basically it manages =
primary_conn_info of some nodes to provide some fault-tolerance =
properties. I'd start to design from here, not from Raft paper.


Best regards, Andrey Borodin.=