| From: | Bruce Momjian <bruce(at)momjian(dot)us> |
|---|---|
| To: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
| Cc: | Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com>, Jaime Casanova <jaime(dot)casanova(at)2ndquadrant(dot)com>, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Patch: Write Amplification Reduction Method (WARM) |
| Date: | 2017-02-23 18:23:41 |
| Message-ID: | 20170223182341.GK20486@momjian.us |
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| Lists: | pgsql-hackers |
On Thu, Feb 23, 2017 at 03:03:39PM -0300, Alvaro Herrera wrote:
> Bruce Momjian wrote:
>
> > As I remember, WARM only allows
> > a single index-column change in the chain. Why are you seeing such a
> > large performance improvement? I would have thought it would be that
> > high if we allowed an unlimited number of index changes in the chain.
>
> The second update in a chain creates another non-warm-updated tuple, so
> the third update can be a warm update again, and so on.
Right, before this patch they would be two independent HOT chains. It
still seems like an unexpectedly-high performance win. Are two
independent HOT chains that much more expensive than joining them via
WARM?
--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ As you are, so once was I. As I am, so you will be. +
+ Ancient Roman grave inscription +
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