| From: | Matthew <matthew(at)flymine(dot)org> |
|---|---|
| To: | pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: count * performance issue |
| Date: | 2008-03-11 14:19:09 |
| Message-ID: | Pine.LNX.4.64.0803111407580.20402@aragorn.flymine.org |
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| Lists: | pgsql-performance |
On Tue, 11 Mar 2008, Tino Wildenhain wrote:
>> And certain, qualified definitions of "accurate" as well. Race condition?
>
> You mean in a three-state-logic? null, not null and something different?
True, False, and FILE_NOT_FOUND.
No, actually I was referring to a race condition. So, you find the count
of rows with IS NULL, then someone changes a row, then you find the count
of rows with IS NOT NULL. Add the two together, and there may be rows that
were counted twice, or not at all.
Matthew
--
It's one of those irregular verbs - "I have an independent mind," "You are
an eccentric," "He is round the twist."
-- Bernard Woolly, Yes Prime Minister
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