From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Bruce Momjian <bruce@momjian.us>
Cc: Pavan Deolasee <pavan.deolasee@gmail.com>
Cc: Jaime Casanova <jaime.casanova@2ndquadrant.com>
Cc: Haribabu Kommi <kommi.haribabu@gmail.com>
Cc: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: Patch: Write Amplification Reduction Method (WARM)
Date: Thu, 23 Feb 2017 15:45:24 -0300
Message-ID: <20170223184524.icdwoh34txoob2ja@alvherre.pgsql> (raw)
In-Reply-To: <20170223183032.GL20486@momjian.us>
List-Unsubscribe: <mailto:majordomo@postgresql.org?body=unsub%20pgsql-hackers>
Bruce Momjian wrote:
> Well, let's walk through this. Let's suppose you have three updates
> that stay on the same page and don't update any indexed columns --- that
> would produce a HOT chain of four tuples. If you then do an update that
> changes an indexed column, prior to this patch, you get a normal update,
> and more HOT updates can be added to this. With WARM, we can join those
> chains
With WARM, what happens is that the first three updates are HOT updates
just like currently, and the fourth one is a WARM update.
> and potentially trim the first HOT chain as those tuples become
> invisible.
That can already happen even without WARM, no?
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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Cc: alvherre@2ndquadrant.com, bruce@momjian.us, pavan.deolasee@gmail.com, jaime.casanova@2ndquadrant.com, kommi.haribabu@gmail.com, tomas.vondra@2ndquadrant.com
Subject: Re: Patch: Write Amplification Reduction Method (WARM)
In-Reply-To: <20170223184524.icdwoh34txoob2ja@alvherre.pgsql>
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