Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Usenet -> c.d.o.server -> Re: oracle - mysql comparison

Re: oracle - mysql comparison

From: Dan <guntermannxxx_at_verizon.com>
Date: Wed, 21 Jul 2004 03:46:41 GMT
Message-ID: <BGlLc.33060$lz2.15337@nwrddc03.gnilink.net>

"Daniel Morgan" <damorgan_at_x.washington.edu> wrote in message news:1090378283.651396_at_yasure...
> Volker Hetzer wrote:
>
> > "VC" <boston103_at_hotmail.com> schrieb im Newsbeitrag
news:RfdLc.109372$WX.92600_at_attbi_s51...
> >
> >>Here's another textbook example for you:
> >>==
> >>There are two linked accounts (id=1 and id=2) in a bank. A transaction
> >>might look as follows:
> >>
> >>== withdraw from 1
> >>select amount into x from accounts where id=1
> >>select amount into y from accounts where id=2
> >>if x+y >= withdrawal then update accounts set amount=amount-withdrawal
> >>where id=1
> >>commit
> >>=====
> >>
> >>Any commercial locking scheduler will handle the scenario correctly.
Oracle
> >>won't.
> >
> > Sorry for butting in but I'm just trying to learn here, so what would go
wrong?
> > And what about "select for update" in oracle? It's supposed to lock the
rows it hits.
> >
> > Lots of Greetings!
> > Volker
>
> You are correct and VC, as I earlier stated to him, is demonstrating far
> less than a robust understanding of transaction processing: Lots of
> smoke but no fire.
>

VC already explained it. Serializable schedules are always preferrable to serialized schedules. The 'FOR UPDATE' clause is a hack that only results in a *serialized* sequence of transactions.

Again, you need to understand the difference between serialized and serializable, and you need to either take a basic database course or read a textbook. All I see from you is a bunch of hand waving. If someone asks a question in the middle of some private war of yours, you latch on like the guy is backing you up. VC gave more than ample evidence and he was very patient in explaining it to you, but you chose to ignore him. Why? Can you address issues in a more apolitical manner? Do you always have to have the last word, even if it makes you look like a moron?

The emporer really has no clothes.

> Daniel Morgan
>

- Dan Received on Tue Jul 20 2004 - 22:46:41 CDT

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US