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From: Tino Wildenhain <tino@wildenhain.de>
To: Matthew <matthew@flymine.org>
Cc: pgsql-performance@postgresql.org
Subject: Re: count * performance issue
Date: Tue, 11 Mar 2008 15:01:06 +0100
Message-ID: <47D690A2.2090509@wildenhain.de> (raw)
In-Reply-To: <Pine.LNX.4.64.0803111355440.20402@aragorn.flymine.org>
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Hi,

Matthew wrote:
> On Tue, 11 Mar 2008, Bill Moran wrote:
> 
>> In response to "Robins Tharakan" <tharakan@gmail.com>:
>>> Sorry, if I am missing something here, but shouldn't something like this
>>> allow us to get a (fast) accurate count ?
>>>
>>> SELECT COUNT(*) from table WHERE indexed_field IS NULL
>>> +
>>> SELECT COUNT(*) from table WHERE indexed_field IS NOT NULL
>>
>> For certain, qualified definitions of "fast", sure.
> 
> And certain, qualified definitions of "accurate" as well. Race condition?

You mean in a three-state-logic? null, not null and something different?

;-)

Tino

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