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Re: [HACKERS] Patch: Write Amplification Reduction Method (WARM) - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: [HACKERS] Patch: Write Amplification Reduction Method (WARM)
Date
Msg-id 20170223182341.GK20486@momjian.us
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In response to Re: [HACKERS] Patch: Write Amplification Reduction Method (WARM)  (Alvaro Herrera <alvherre@2ndquadrant.com>)
Responses Re: [HACKERS] Patch: Write Amplification Reduction Method (WARM)  (Alvaro Herrera <alvherre@2ndquadrant.com>)
Re: [HACKERS] Patch: Write Amplification Reduction Method (WARM)  (Pavan Deolasee <pavan.deolasee@gmail.com>)
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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@momjian.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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