Re: computational model of transactions

> Let's say that you're account starts out with a balance of $550.
>
> At time T1 a transaction is started to post a check for $500.
> At time T2 a transaction is started to post a check for $100.
> At time T3 a transaction is started to post a check for $75.
> At time T4 the $100 transaction completes, recording a balance of $450.
> At time T5 the $75 transaction completes, recording a balance of $375.
> At time T6 the $500 transaction completes, recording a balance of $-125.

The error is that these transactions are "allowed to run concurrently".

Since each of them wants to update the very same resource (the same attribute of the same tuple of the same relvar), these transactions should be serialized anyway.

No two things can be in the same place at the same time. Received on Fri Aug 04 2006 - 09:51:58 CEST