Re: a union is always a join!

"Brian Selzer" <brian_at_selzer-software.com> wrote in message news:wLsrl.14888$as4.3977_at_nlpi069.nbdc.sbc.com... >

>> that states what is happening. Whenever nothing is happening, what has
>> been the case /is/ the case. For example, if Joe has been second in line

Let's look at "whenever nothing is happening" in more detail. I submit that, at a point in time where there are no transactions in progress, that "nothing is happening". Further, I submit that, if serializability is the criterion for concurrency management, then the DBMS ensures that the view of the database is as if "nothing is happening", during a transaction, except for the actions of that transaction. Every other transaction can be seen as being completed "in the past" or beginning "in the future".

So, if the transactions can be serialized, each transaction sees the database as if "nothing is happening". If you agree with all that, then why isn't your point moot? If you don't agree, where don't you agree? Received on Wed Mar 04 2009 - 17:50:01 CET