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From: Robert Haas <[email protected]>
To: Tom Lane <[email protected]>
Cc: Simon Riggs <[email protected]>
Cc: Ron Mayer <[email protected]>
Cc: Euler Taveira de Oliveira <[email protected]>
Cc: [email protected] <[email protected]>
Subject: Re: explain analyze rows=%.0f
Date: Tue, 2 Jun 2009 10:56:59 -0400
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
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...Robert

On Jun 2, 2009, at 10:38 AM, Tom Lane <[email protected]> wrote:

> Robert Haas <[email protected]> writes:
>> On Jun 2, 2009, at 9:41 AM, Simon Riggs <[email protected]>  
>> wrote:
>>> 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.
>
>> Bingo.
>
> Uh, the planner's estimate *is* an integer.  What was under discussion
> (I thought) was showing some fractional digits in the case where  
> EXPLAIN
> ANALYZE is outputting a measured row count that is an average over
> multiple loops, and therefore isn't necessarily an integer.  In that
> case the measured value can be considered arbitrarily precise ---  
> though
> I think in practice one or two fractional digits would be plenty.

We're in violent agreement here.

...Robert

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