Re: MV Keys

From: mAsterdam <mAsterdam_at_vrijdag.org>
Date: Sat, 04 Mar 2006 00:07:51 +0100
Message-ID: <4408cbe8$0$11072$e4fe514c_at_news.xs4all.nl>

vc wrote:

> mAsterdam wrote:

>>vc wrote:
>>>mAsterdam wrote:
>>>>Marshall Spight wrote:
>>>>>Jon Heggland wrote:
>>>>>
>>>>>The relational operators don't handle lists very well.
>>>>>
>>>>>myList.removeAt(3)
>>>>>
>>>>>vs.
>>>>>
>>>>>BEGIN
>>>>>delete from MyList where Index = 3;
>>>>>update MyList set Index = Index - 1 where Index > 3;
>>>>>COMMIT
>>>>
>>>>
>>>>Aside (the example surely illustrates your point)
>>>>could this removeAt operation possibly be useful
>>>>in a concurrent environment?
>>>>
>>>>You'ld never know which item you are going to scratch -
>>>>somebody else could have just done myList.removeAt(2).
>>>
>>>
>>>What happened to concurrency contro in your hypothetical system ?
>>
>>Assuming MVCC the item which was the third item
>>in MyList at transaction time would be removed.
>>Results may be very unpleasant - that was my point -
>>but would this constitute a CC failure?
>
> Sure it would. It would mean that your database CC is broken.

In what way? Please explain. Received on Sat Mar 04 2006 - 00:07:51 CET