Re: ACID et al

paul c wrote:
> 3) Assume the engine is single-threaded. Two users' messages can't
> interleave their actions between each other, ie., messages are
> 'single-file'.

This looks like a lock to me. A rather coarse-grained one.

> 4) Assume that a message to the engine includes all the db actions for
> some 'business' transaction. These actions might include re-iterated
> reads of rows that were issued in an earlier 'query' message, as well as
> possibly the values that were returned earlier, as well as update actions.
[...]
> with customer and or balance rows). The second updating message (which
> might occur many minutes or hours after the first) might reiterate the
> original queries in some form, perhaps including certain data such as
> 'balance = $500' which would be asserted to still be true before the
> debit is made persistent.

This looks like an optimistic lock, with the responsibility of enforcing it pushed to the application.

Daniel Received on Mon Dec 05 2005 - 09:55:44 CST