Re: Improving connection scalability: GetSnapshotData()

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: "Jonathan S(dot) Katz" <jkatz(at)postgresql(dot)org>, Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru>, Andres Freund <andres(at)anarazel(dot)de>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, Peter Geoghegan <pg(at)bowt(dot)ie>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, David Rowley <dgrowleyml(at)gmail(dot)com>
Subject: Re: Improving connection scalability: GetSnapshotData()
Date: 2020-04-08 22:06:23
Message-ID: 20200408220623.GA23414@momjian.us
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On Wed, Apr 8, 2020 at 09:44:16AM -0400, Robert Haas wrote:
> I don't know what the right thing to do is. I agree with everyone who
> says this is a very important problem, and I have the highest respect
> for Andres's technical ability. On the other hand, I have been around
> here long enough to know that deciding whether to allow late commits
> on the basis of how much we like the feature is a bad plan, because it
> takes into account only the upside of a commit, and ignores the
> possible downside risk. Typically, the commit is late because the
> feature was rushed to completion at the last minute, which can have an
> effect on quality. I can say, having read through the patches
> yesterday, that they don't suck, but I can't say that they're fully
> correct. That's not to say that we shouldn't decide to take them, but
> it is a concern to be taken seriously. We have made mistakes before in
> what we shipped that had serious implications for many users and for
> the project; we should all be wary of making more such mistakes. I am
> not trying to say that solving problems and making stuff better is NOT
> important, just that every coin has two sides.

If we don't commit this, where does this leave us with the
old_snapshot_threshold feature? We remove it in back branches and have
no working version in PG 13? That seems kind of bad.

--
Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EnterpriseDB https://enterprisedb.com

+ As you are, so once was I. As I am, so you will be. +
+ Ancient Roman grave inscription +

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