pg.ddx.io  pgsql-hackers@postgresql.org mailing list archive  

help / color / mirror / Atom feed
From: Bruce Momjian <bruce@momjian.us>
To: Andres Freund <andres@anarazel.de>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: Jonathan S. Katz <jkatz@postgresql.org>
Cc: Alexander Korotkov <a.korotkov@postgrespro.ru>
Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Cc: Peter Geoghegan <pg@bowt.ie>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Thomas Munro <thomas.munro@gmail.com>
Cc: David Rowley <dgrowleyml@gmail.com>
Subject: Re: Improving connection scalability: GetSnapshotData()
Date: Wed, 8 Apr 2020 20:31:56 -0400
Message-ID: <20200409003156.GA9858@momjian.us> (raw)
In-Reply-To: <20200408222534.56ys4lt7xd3dvgqu@alap3.anarazel.de>
References: <CAPpHfdthCaCt09Nnj6oCYq93_PUfJSw5QOLGgnid3qJsEWXuGA@mail.gmail.com>
	<20200406133959.viql5fqecog6mppj@alap3.anarazel.de>
	<20200406235228.lnxcau2wgocnnn22@alap3.anarazel.de>
	<20200407121503.zltbpqmdesurflnm@alap3.anarazel.de>
	<20200408124318.amzvnpsqhy747wqp@alap3.anarazel.de>
	<CAPpHfdt78x-aOhbTdY01HJ-ydM9ZSo-sRJNi0pwk7WmWd0xxAA@mail.gmail.com>
	<07c6af6c-c30d-52e4-8716-e3688c3ef265@postgresql.org>
	<CA+TgmobObXx2-JZo_eoRVLgfNF29V=AOP69U=_frcy5+YCPGvA@mail.gmail.com>
	<20200408220623.GA23414@momjian.us>
	<20200408222534.56ys4lt7xd3dvgqu@alap3.anarazel.de>

On Wed, Apr  8, 2020 at 03:25:34PM -0700, Andres Freund wrote:
> Hi,
> 
> On 2020-04-08 18:06:23 -0400, Bruce Momjian wrote:
> > 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.
> 
> I don't think this patch changes the situation for
> old_snapshot_threshold in a meaningful way.
> 
> Sure, this patch makes old_snapshot_threshold scale better, and triggers
> fewer unnecessary query cancellations.  But there still are wrong query
> results, the tests still don't test anything meaningful, and the
> determination of which query is cancelled is still wrong.

Oh, OK, so it still needs to be disabled.  I was hoping we could paint
this as a fix.

Based on Robert's analysis of the risk (no SQL syntax, no storage
changes), I think, if you are willing to keep working at this until the
final release, it is reasonable to apply it.

-- 
  Bruce Momjian  <bruce@momjian.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 +





view thread (102+ messages)  latest in thread

Message-ID: <20200409003156.GA9858@momjian.us>
Permalink:  ../20200409003156.GA9858@momjian.us/
Also on:    postgresql.org/message-id/20200409003156.GA9858@momjian.us

 · 

reply
Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: pgsql-hackers@postgresql.org
  Cc: bruce@momjian.us, andres@anarazel.de, robertmhaas@gmail.com, jkatz@postgresql.org, a.korotkov@postgrespro.ru, pg@bowt.ie, alvherre@2ndquadrant.com, thomas.munro@gmail.com, dgrowleyml@gmail.com
  Subject: Re: Improving connection scalability: GetSnapshotData()
  In-Reply-To: <20200409003156.GA9858@momjian.us>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox