Re: Record Locking ???
Date: Mon, 12 May 2003 10:40:39 -0500
Message-ID: <3EBFC077.2BDCBBE_at_ram.lmtas.lmco.com>
Viki,
A great response !
Mike
viki wrote:
> froliol_at_yahoo.com (Louis Frolio) wrote in message news:<94c28610.0305081211.75b0bf74_at_posting.google.com>...
> > You should not let this developer do any record locking. The Oracle
> > RDBMS will handle all record locking much more efficiently than any
> > user could. What is the motivation for the user wanting to lock a
> > record? Until he/she issues a commit or rollback the data(prior to
> > the new data issued by this user) in that record will still be able to
> > be viewed by another user. Dirty reads are not possible in Oracle.
> >
> > Louis.
> >
> >
> > Walt <walt_at_boatnerd.com.invalid> wrote in message news:<3EB97CEF.EB7E177A_at_boatnerd.com.invalid>...
> > > TurkBear wrote:
> > > > Michael Hill <hillmw_at_ram.lmtas.lmco.com> wrote:
> > > >
> > > > >I have a Coldfusion web application that makes calls to Oracle tables,
> > > > >inserts, updates, et. al and one of my users wants to add "Record
> > > > >Locking". I am thinking this is not practical and is only valid in a
> > > > >client-server environment.
> > > > >
> > > > >Am I wrong?
> > > > >
> > > > >Comments?
> > > > Ask your user why he wants to manually do what Oracle will handle automatically?
> > > >
> > > > Just curious...
> > >
> > > While Oracle handles row locking automagically within a transaction, the
> > > issue as I see it is how to preserve a transaction across multiple web
> > > requests. i.e. the interaction is something like
> > >
> > > 1. begin a transaction
> > > 2. get the data with a select for update
> > > 3. update the data
> > > 4. commit or rollback the transaction
> > >
> > > The issue is item 2 and item 3 are handled in separate web requests -
> > > when the user comes back to update the data, how does he pick up the
> > > transaction that he opened in item 1?
> > >
> > > There's no reason that I see that would make this technically
> > > impossible, but I have no idea how to do it in Cold Fusion.
>
> While working on a web-based application, there is no straight forward
> means to lock records. The reason for this is the statelessness of web
> based applications. The web browser sends a request and the web server
> responds to the request. The transaction is restricted to this
> duration and all locks holds only within this transaction.
>
> The only way in which you can achieve locking in such a system is by
> what is called as optimistic locking, where you maintain a time stamp
> column (date and time of last update) in every table. When a page is
> requested, the date and time of last update of the record is also
> sent. Now, when the user updates the record, check if the time stamp
> of the record has changed. If yes you can throw an error.
>
> I guess this should work in you case as well.
>
> Cheers
> Viki
Received on Mon May 12 2003 - 17:40:39 CEST