Re: computational model of transactions
Date: Tue, 01 Aug 2006 20:19:19 GMT
Message-ID: <bHOzg.31848$pu3.424658_at_ursa-nb00s0.nbnet.nb.ca>
paul c wrote:
>> paul c wrote: >> ... >> What if one combines multiple logical units of work into a single >> transaction? I have seen this done for performance in batch processes >> to faciliate effective physical buffering etc. With Marshall's >> proposal, this would not be possble.
>
> So have I, and the batch process was usually serialized in one way or
> another, either by suspending certain other transactions or even by
> kicking all users off the system.
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.
Thus, the batch might issue 10 commits for 1000 logical units of work by only committing after every 100th one. For larger logical units of work, the batch might issue 100 commits by committing after every 10th one.
There is a performance tradeoff between how much of the log is used for uncommitted transactions vs. how efficiently the batch uses the network resources. Plus, one has to consider that a rollback will revert multiple logical units of work. Received on Tue Aug 01 2006 - 22:19:19 CEST