Re: computational model of transactions
From: paul c <toledobythesea_at_oohay.ac>
Date: Wed, 02 Aug 2006 00:57:47 GMT
Message-ID: <fMSzg.305148$Mn5.193880_at_pd7tw3no>
>
> Indeed. In fact, it was possible to run multiple batches in parallel.
> This makes concurrency very relevant not moot.
>
>
> I think luw is
>
> A logical unit of work must be treated as atomic. Thus, if part of the
> work is rolled back, it must all be rolled back. This is how one usually
> identifies what must go into a single transaction.
>
> Combining an integral number of logical units of work into a single
> transaction, however, does not introduce any risk of inconsistency. That
> is, there is no theory or argument preventing one from combining them.
> Marshall's suggestion, on the other hand, would prevent them.
>
Date: Wed, 02 Aug 2006 00:57:47 GMT
Message-ID: <fMSzg.305148$Mn5.193880_at_pd7tw3no>
Bob Badour wrote:
> paul c wrote:
>
>> paul c wrote: >> >>> Bob Badour wrote: >>> ... >>> >>>>>>> While that's sometimes necessary, the batch processes I referred >>>>>>> to did not all do that. They just grouped multiple logical units >>>>>>> of work together before issuing a commit. Serializing was handled >>>>>>> by the normal concurrency features and isolation level. >>>>>>> ... >>> >>> In that case, you are talking about serialization and not recognizing >>> it. >>> >>> p >> >> (To clarify, if the so-called luw's could have been run in parallel >> with an acceptable result, the issue of concurrency is moot.
>
> Indeed. In fact, it was possible to run multiple batches in parallel.
> This makes concurrency very relevant not moot.
>
>
> I think luw is
>> synonomous with transaction in Gray's sense, even though I know some >> programmers think program trumps transaction. But then I think >> programmers are servants, not arbiters.)
>
> A logical unit of work must be treated as atomic. Thus, if part of the
> work is rolled back, it must all be rolled back. This is how one usually
> identifies what must go into a single transaction.
>
> Combining an integral number of logical units of work into a single
> transaction, however, does not introduce any risk of inconsistency. That
> is, there is no theory or argument preventing one from combining them.
> Marshall's suggestion, on the other hand, would prevent them.
>
Yes, as I recall, Marshall talked of more than one transaction. But if certain multiple transactions have the same result as one, there is no issue of concurrency, IMHO.
p Received on Wed Aug 02 2006 - 02:57:47 CEST