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Re: Read-write model

From: mAsterdam <mAsterdam_at_vrijdag.org>
Date: Sat, 03 Apr 2004 10:43:13 +0200
Message-ID: <406e7923$0$559$e4fe514c@news.xs4all.nl>


Karsten Wutzke wrote:

> I have an important question about scheduling and the underlying
> read-write model:
>
> Is it right, that the read-write model dictates, that there are no
> redundant read or write operations on the same database object per
> transaction, or better, only one read or write on a specific database
> object per transaction???
>
> TA1 = r(x) w(y) r(x) w(x) -> the 2nd r(x) would be invalid

If r(x) is not garanteed to return the same values twice (google for read-consistency), there are problems, r(x) != r(x) Time and timevariance are important to these problems. To uncover those it might help to make assumptions about time explicit. r(t1, x) != r(t2, x).

Just my 2 Eurocents. Received on Sat Apr 03 2004 - 02:43:13 CST

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