Subject: Re: explain analyze rows=%.0f
From: Simon Riggs <simon@2ndQuadrant.com>
To: Ron Mayer <rm_pg@cheapcomplexdevices.com>
Cc: Euler Taveira de Oliveira <euler@timbira.com>,
	Robert Haas <robertmhaas@gmail.com>,
	"pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
In-Reply-To: <4A249CE9.6050708@cheapcomplexdevices.com>
References: <603c8f070905281830g2e5419c4xad2946d149e21f9d@mail.gmail.com>
	<4A1F4FD5.7060204@timbira.com>
	<4A249CE9.6050708@cheapcomplexdevices.com>
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Date: Tue, 02 Jun 2009 14:41:00 +0100
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On Mon, 2009-06-01 at 20:30 -0700, Ron Mayer wrote:

> What I'd find strange about "6.67 rows" in your example is more that on
> the estimated rows side, it seems to imply an unrealistically precise estimate
> in the same way that "667 rows" would seem unrealistically precise to me.
> Maybe rounding to 2 significant digits would reduce confusion?

You're right that the number of significant digits already exceeds the
true accuracy of the computation. I think what Robert wants to see is
the exact value used in the calc, so the estimates can be checked more
thoroughly than is currently possible.

-- 
 Simon Riggs           www.2ndQuadrant.com
 PostgreSQL Training, Services and Support