Re: Informix vs. Sybase vs. Oracle vs. (gasp) MS SQL Server

Pablo Sanchez wrote:

> I phoned two airline companies: United and US Air. I

	Wow! Someone's bothering to do some leg work rather than
	just making blind assumptions.

> interviewed the person taking reservations and here are the
> responses:
>
> US Air:
> -------
> You can view the list of available seats and present that to
> the customer. If the customer requests that seat, they go
> through the reservation process and that seat *may* be
> swiped by another office. That is, there's no lock that is
> placed on that seat.

	I can't see much point in locking all the seats in the
	expectation that one may be reserved. I don't expect
	the display to show reservations being taken in real
	time or can it? (Messaging between a backend and a
	registered app?)

> I interpreted this in db terms as follows:
>
> tx #1:
>
> select list of available seats for flight number

	Isn't the display graphical and shows all seats
	and their current status?

> tx #2:
>
> begin tx
> update seat_table where flight_number is the one we are on
> and it's not already taken
> if taken, failure ... rollback tran
> else, print "happy days are here"
>
> I believe that this is SABRE.

        Careful, thats an assumption.

> United Airlines
> ---------------
> You can lock a seat if you have a specific seat in mind
> without making a reservation yet. You can make the
> reservation and have that seat. If the system crashes
> between locking the seat and making the reservation, the
> seat remains locked. (I found this interesting).

        What if its already locked?

> I interpret this in db terms as follows:
>
> tx #1:
>
> select list of seats....
>
> tx #2:
>
> update seat_table .... (as before)
>
> tx #3:
>
> update reservation_table

	What bugs me is that you STILL get overbooking!
	Is there anyone that can explain that? (Not that
	I'm complaining mind you. They usually promote
	you up.)

-am Received on Tue Dec 02 1997 - 00:00:00 CET