[elephant-devel] DB Transactions and UI

[Evrim Ulu]

Ian Eslick wrote:

> Just a few short comments:
>
> 1) I think that DBs are designed for certain kinds of short-running
> transactions, but over time have been co-opted into supporting
> longer and more complex ones.
>
> 2) User interaction takes place in a completely different domain
> and I think that the constraints of that domain should not be
> conflated with the low-level DB semantics.
>
> 3) As for user interactions like checkout; I think you probably
> want to implement your own dependency tracking, for example a
> multi-stage process for buying tickets. Here we use two levels of
> transactions and a DB field to perform application-level locking.
>
>
What about the below situation:

Assume there is list of open chairs of a cinema hall, user selects the
chair that he wants to buy, if the transaction is short, (ie
non-locking) and at the same time if another user buys that chair,
who's the owner of the chair really?

Application layer locking is painful to implement and adds several
transient states. I've seen only a single approach  called "Namos"
targetting these kinds of problems, unfortunately no implementations
exist.


evrim.