Re: cdt glossary 0.1.1 [Transaction]

mAsterdam wrote:
> paul c wrote:
>

>> mAsterdam wrote:
>>
>>> ...
>>> Hi paulc, sorry, I only have the first edition.
>>> ...
>>
>>
>> I seem to remember that the first edition had more or less the same 
>> chapter four.  Anyway, the authors have kindly made it publicly 
>> available at http://www.dcs.warwick.ac.uk/~hugh/TTM/APPXA.pdf

I wasn't suggesting it did. As far as I know, "order of work" is not a relational issue, nor is a transaction a relational concept any more than invoices are. Wondering why they aren't part of RT is like asking why the RM isn't based on a state machine.

I would say "order of work" is a language concept and is not necessarily required by all possible languages. I also think it is not necessarily part and parcel of a transaction concept. (For example, my preferred language would not require statements to be ordered by the programmer, even though the machine might have to order them.) Saying that one can't have an atomic group of statements that either all complete successfully or none of them completes without the programmer's statements following some order is like saying that relations must be stored in the same table form that they might be displayed in.

(To my mind, that appendix lays a basis for the bare naked relational model and includes formal definitions too. Unfortunately for those who don't have one of three printed editions, the chapter five of the third edition that is on the TTM web site doesn't have the section "mapping the relational operators" section that the second edition's chapter five included (eg., that's where UNION/INSERT are defined in terms of <OR>).   I guess it is in some other chapter of the print version of the third edition, at least I hope so since it rounds out the bare naked model for me.)

p Received on Fri Apr 20 2007 - 00:33:01 CEST