"Transactions are bad, real bad" - discuss

From: Jonathan Leffler <jleffler_at_earthlink.net>
Date: Tue, 29 Apr 2003 06:06:56 GMT
Message-ID: <3EAE16E6.2070803_at_earthlink.net>

In an article under the thread "Do Data Models Need to [be] built on a Mathematical Concept?", Paul Vernon commented:
>>transactions
>
> Dead wrong. Transactions are bad, real bad. In short they are not
> compatible with the 'arrow of time'. They let you freeze time and
> that is not a good model of reality. Start a new thread if you want
> to discuss the details, I've a draft paper on the subject and a
> could do with some intelligent challenges to sharpen up my
> argument.

Herewith, a new thread - unless someone else got there first.

I'm sympathetic to the Date/Darwen view (espoused in The Third Manifesto and in Temporal Data) that a single statement should be the scope of a transaction, once you allow what would currently be a sequence of statements to be treated as a unit -- using the SQL notation:

UPDATE Table1 SET ... ,
UPDATE Table2 SET ... ,
INSERT INTO Table3 ... ,
DELETE FROM Table4 ...;

All four operations are part of a single compound statement and collectively form a single transaction.

Is that anything remotely resembling what you're thinking, Paul?

I assume that you're not arguing that it is unnecessary to have something akin to a transaction, (or a saga, or a set of compensating actions), in the sequence:

BEGIN WORK;
UPDATE Accounts

     SET Balance = Balance - 1000000
     WHERE AcountOwner = 'Paul Vernon';
UPDATE Accounts
     SET Balance = Balance + 1000000
     WHERE AccountOwner = 'Jonathan Leffler';

COMMIT WORK; If the two UPDATE operations are not treated somewhat atomically - if the first can succeed and yet the second can fail (boo, hoo) without somehow undoing the first - then Paul is 1000000 currency units (GBP) out of pocket (and so am I, but I didn't have them in the first place, whereas maybe Paul did, and more significantly, maybe he now owes the bank those currency units he didn't already have in his posession).

-- 
Jonathan Leffler                   #include <disclaimer.h>
Email: jleffler_at_earthlink.net, jleffler_at_us.ibm.com
Guardian of DBD::Informix v2003.04 -- http://dbi.perl.org/

Received on Tue Apr 29 2003 - 08:06:56 CEST