Re: MV Keys
From: mAsterdam <mAsterdam_at_vrijdag.org>
Date: Tue, 07 Mar 2006 00:22:16 +0100
Message-ID: <440cc41e$0$11063$e4fe514c_at_news.xs4all.nl>
>
>
>
>
> (insert into OurSharedList(Existing, New)
> select hopefullyexisting item as Existing, new item as New
> from OurSharedList
> where Existing=hopefullyexisting item
> union
> select new item as Existing, New
> from OurSharedList
> where Existing=hopefullyexisting item) ,
> (delete from OurSharedList where Existing=hopefullyexisting item)
Date: Tue, 07 Mar 2006 00:22:16 +0100
Message-ID: <440cc41e$0$11063$e4fe514c_at_news.xs4all.nl>
x wrote:
> mAsterdam wrote:
>
>>Marshall Spight wrote: >> >>>mAsterdam wrote: >>> >>>>Aside (the example surely illustrates your point) >>>>could this removeAt operation possibly be useful >>>>in a concurrent environment? >>> >>>For sure. >> >>I don't (yet? :-) see how it can be useful etc. by itself. >>A little namechange to emphasize the multi-somethingness: >> >>OurSharedList.removeAt(index) has more serious >>sharing problems than, say: >>OurSharedList.removeItem(item) >> >>ISTM the index loses its meaning when I'm not >>in sole control of the list.
>
>
>>Hmm... OurSharedList.insertafter(hopefullyexisting item, new item)
>
>
> (insert into OurSharedList(Existing, New)
> select hopefullyexisting item as Existing, new item as New
> from OurSharedList
> where Existing=hopefullyexisting item
> union
> select new item as Existing, New
> from OurSharedList
> where Existing=hopefullyexisting item) ,
> (delete from OurSharedList where Existing=hopefullyexisting item)
I wonder if I understand why you delete the (hopefully) existing item from OurSharedList (and insert it back in when it was there originally). Guess: No simpler way to establish wether it's there and have the query fail when it's not? Received on Tue Mar 07 2006 - 00:22:16 CET