Date: Tue, 11 Feb 2014 20:03:47 +0100
From: Andres Freund <andres@2ndquadrant.com>
To: Bruce Momjian <bruce@momjian.us>
Cc: Robert Haas <robertmhaas@gmail.com>, Jim Nasby <jim@nasby.net>,
 Alvaro Herrera <alvherre@2ndquadrant.com>,
 Peter Geoghegan <peter@2ndquadrant.com>,
 Tom Lane <tgl@sss.pgh.pa.us>, Andrew Dunstan <andrew@dunslane.net>,
 PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: [PERFORM] encouraging index-only scans
Message-ID: <20140211190347.GL15246@awork2.anarazel.de>
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On 2014-02-11 13:41:46 -0500, Bruce Momjian wrote:
> Wait longer for what?  Anti-xid-wraparound vacuum?

Yes.

> Is using VACUUM for these cases documented?  Should it be?

No idea, it seems to be part of at least part of the folkloric
knowledge, from what I see at clients.

> > I am not saying it shouldn't be improved, I just don't see the point of
> > bringing it up while everyone is busy with the last CF and claiming it
> > is unusable and that stating that it is surprisising that nobody really
> > cares.

> Well, I brought it up in September too. My point was not that it is a
> new issue but that it has been such an ignored issue for two years.  I
> am not asking for a fix, but right now we don't even have a plan on how
> to improve this.

Coming up with a plan for this takes time and discussion, not something
we seem to have aplenty of atm. And even if were to agree on a plan
right now, we wouldn't incorporate it into 9.4, so what's the point of
bringing it up now?

> I still don't see how this is FUD, and you have not explained it to me. 
> This is a known limitation for two years, not documented (?), and with
> no TODO item and no plan on how to improve it.  Do you want to declare
> such cases FUD and just ignore them?  I don't see how that moves us
> forward.

Claiming something doesn't work while it just has manageable usability
issues doesn't strike me as a reasonable starting point. If it bugs
somebody enough to come up with a rough proposal it will get fixed...

Greetings,

Andres Freund

-- 
 Andres Freund	                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services


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