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From: Bruce Momjian <bruce@momjian.us>
To: Andres Freund <andres@2ndquadrant.com>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: Jim Nasby <jim@nasby.net>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Peter Geoghegan <peter@2ndquadrant.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Andrew Dunstan <andrew@dunslane.net>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: [PERFORM] encouraging index-only scans
Date: Tue, 11 Feb 2014 13:23:19 -0500
Message-ID: <20140211182319.GF2289@momjian.us> (raw)
In-Reply-To: <20140211175410.GF31598@awork2.anarazel.de>
References: <20130907053449.GE626072@alap2.anarazel.de>
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	<CA+TgmoZQyt253OA_ssD6OVs8o0-RkRz3eK6qZz3Utwp-2QVf6A@mail.gmail.com>
	<20140201032207.GD31141@momjian.us>
	<CA+TgmoYOAzNKWKdkNcq50MFQKdgSt1ESR6zxb8XKCiNO6YBX2A@mail.gmail.com>
	<20140211155607.GB2289@momjian.us>
	<CA+TgmobeczQK0LhgVz_bSs7M4iTbCP=sfK8=6yDuCpwtOiuCCw@mail.gmail.com>
	<20140211171213.GE2289@momjian.us>
	<20140211175410.GF31598@awork2.anarazel.de>
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On Tue, Feb 11, 2014 at 06:54:10PM +0100, Andres Freund wrote:
> On 2014-02-11 12:12:13 -0500, Bruce Momjian wrote:
> > Yes, that pretty much sums it up.  We introduced index-only scans in 9.2
> > (2012) but they still seem to be not usable for insert-only workloads
> > two years later.  Based on current progress, it doesn't look like this
> > will be corrected until 9.5 (2015).  I am kind of confused why this has
> > not generated more urgency.
> 
> I think this largely FUD. They are hugely beneficial in some scenarios
> and less so in others. Just like lots of other features we have.

I don't understand.  Index-only scans are known to have benefits --- if
an insert-only workload can't use that, why is that acceptable?  What is
fear-uncertainty-and-doubt about that?  Please explain.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + Everyone has their own god. +


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  Cc: bruce@momjian.us, andres@2ndquadrant.com, robertmhaas@gmail.com, jim@nasby.net, alvherre@2ndquadrant.com, peter@2ndquadrant.com, tgl@sss.pgh.pa.us, andrew@dunslane.net, pgsql-hackers@postgresql.org
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