Re: [COMMITTERS] pgsql: Fix freezing of a dead HOT-updated tuple

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Andres Freund <andres(at)anarazel(dot)de>
Cc: Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, "Wood, Dan" <hexpert(at)amazon(dot)com>, Peter Geoghegan <pg(at)bowt(dot)ie>, pgsql-committers <pgsql-committers(at)postgresql(dot)org>, "Wong, Yi Wen" <yiwong(at)amazon(dot)com>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [COMMITTERS] pgsql: Fix freezing of a dead HOT-updated tuple
Date: 2017-11-02 12:25:27
Message-ID: CA+Tgmob1bvRwMK=V6e_C9RrF1G409MiEG7xsKKrUvsTmm1SsFQ@mail.gmail.com
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-committers pgsql-hackers

On Thu, Nov 2, 2017 at 4:50 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> I think a5736bf754c82d8b86674e199e232096c679201d might be dangerous in
> the face of previously corrupted tuple chains and pg_upgraded clusters -
> it can lead to tuples being considered related, even though they they're
> from entirely independent hot chains. Especially when upgrading 9.3 post
> your fix, to current releases.

I think this is a key point. If the new behavior were merely not
entirely correct, we could perhaps refine it later. But it's not only
not correct - it actually has the potential to create new problems
that didn't exist before those commits. And if we release without
reverting those commits then we can't change our mind later.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

In response to

Browse pgsql-committers by date

  From Date Subject
Next Message Alvaro Herrera 2017-11-02 12:49:47 Re: pgsql: Fix freezing of a dead HOT-updated tuple
Previous Message Andres Freund 2017-11-02 11:20:19 Re: pgsql: Fix freezing of a dead HOT-updated tuple

Browse pgsql-hackers by date

  From Date Subject
Next Message Ildus Kurbangaliev 2017-11-02 12:28:36 Re: Custom compression methods
Previous Message Andres Freund 2017-11-02 11:20:19 Re: pgsql: Fix freezing of a dead HOT-updated tuple